Name: In Vivo Telemetry to Record Long-Term Cardiovascular Parameters, Temperature, and Activity in Spinal Cord Injury Rat Models (Video) | JoVE Journal
Uploaded: 2026-01-02T13:30:00.000+00:00
Duration: 9 min 22 s
Description: Learn telemetric implant surgery for long-term cardiovascular, temperature, and activity monitoring in spinal cord injury rat models. This protocol enables continuous physiological recording in freely moving animals.

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5 minutes

The publication was made possible by R01 NS116068, Craig H Nielsen Foundation Fellowship for SK (CHNF 1341200), and University of Kentucky CNS metabolism (CNS-Met) COBRE (P20 GM148326). We would like to acknowledge the Division of Laboratory Animal Resources (DLAR) for its support and cooperation.

Ethical approval was obtained from the University of Kentucky Institutional Animal Care and Use Committee, and the procedures were followed strictly, adhering to the protocol guidelines. Adult female Wistar rats (11-13 weeks, 250-300 g, n = 3 ) were housed at the Division of Lab Animal Research animal facility (University of Kentucky, USA) under standard housing conditions (12/12 light: dark cycle, humidity 30%-70%, temperature 22 &#177; 2 &#176;C) with food and water ad libitum. The reagents and the equipment used are listed in the Table of Materials.
1. Surgical Procedure for telemetric implant placement
NOTE: The placement of the telemetric implant was adapted from Rabchevsky et al. and further optimized to minimize complications and mortality24. The duration of anesthesia and pre-surgical care is approximately 10 minutes. The telemetric implantation surgical procedure varies from 15-30 min. Abdominal and skin incision closure and post-surgical care take 15-20 min. The total duration of the telemetric implant placement surgical procedure is 40-60 min. The reagents and the equipment used for telemetric implantation surgery are listed in the Table of Materials.
<ol>
	<li>Pre-surgery and surgical table preparations
	<ol>
		<li>Autoclave surgical instruments, 16-ply gauze sponges, cotton-tip applicators, and occlusion threads. Fill the pressure catheter tip of the telemetric implant with gel using a syringe.</li>
		<li>Sterilize the implants by sequentially immersing them for 24 h each in detergent, cold sterilant, and 0.9% sodium chloride.</li>
		<li>Keep the implant submerged in 0.9% sodium chloride in a tube labeled with the implant number.</li>
		<li>Place a heating pad on the surgical table and set it to 37-38 &#176;C. Cover the heating pad with surgical underpads, followed by sterile drape towels, to maintain a sterile field during the procedure.</li>
	</ol>
	</li>
	<li>Anesthesia and pre-surgical care
	<ol>
		<li>Anesthetize the rat with isoflurane (3%-4%) and maintain anesthesia at 2% using a Low-Flow Electronic Vaporizer.</li>
		<li>Administer buprenorphine (0.02 mg/kg; analgesic), meloxicam (1 mg/kg; anti-inflammatory), and 5 mL of 0.9% normal saline subcutaneously prior to surgery. Apply lubricating gel to both eyes to prevent corneal dehydration. 
		NOTE: A lower dose of buprenorphine was administered to minimize side effects. The dose has been optimized under veterinary supervision after multiple trials.</li>
	</ol>
	</li>
	<li>Surgical site preparation, incision, and descending aorta exposure
	<ol>
		<li>Shave the abdominal area from 1 cm above the urethral orifice to the mid-abdomen using an electric shaver. Disinfect the exposed skin with povidone iodine scrub, followed by alcohol, and repeat the sequence three times. Place a press-and-seal barrier on the animal and cut a small opening to expose the surgical site. Confirm a surgical plane of anesthesia prior to starting surgery with appropriate monitoring (e.g., toe pinch).</li>
		<li>Make a 4.5-5 cm midline skin incision starting 1-1.5 cm above the urethral orifice, then perform an abdominal incision. Secure the visceral organs with sterilized, saline-soaked 16-ply gauze sponges. Use metal retractors to further secure the organs and to maintain visibility of the region to be operated on.</li>
		<li>Use two fine forceps (microdissection tweezers and mirror-finish forceps) to gently separate the fat bodies and expose the descending aorta and vena cava. Keep one forceps stable to hold the fat bodies, and use the other one to dissect.</li>
	</ol>
	</li>
	<li>Blunt dissection and inspection of telemetric implant
	<ol>
		<li>Perform blunt dissection using the forceps mentioned above, approximately 0.5 cm below the renal artery (used as a landmark) to separate the descending aorta from the vena cava. In addition, separate the descending aorta from the underlying fat bodies to create space for angled forceps insertion.</li>
		<li>Insert angled forceps under the descending aorta through the dissected space between the aorta and the vena cava to ensure that the occlusion thread can pass through.</li>
		<li>Pass a sterile 4-0 silk thread underneath the descending aorta through the dissected space, and secure both ends of the thread using a hemostat.</li>
		<li>Remove the implant from 0.9% sodium chloride, inspect the pressure catheter tip for air bubbles or gaps, and add gel if any of these are present before insertion</li>
	</ol>
	</li>
	<li>Occlusion, insertion, and securing of implant&#160;
	<ol>
		<li>Have another experimenter hold the hemostat at approximately a 45-degree angle, make angular adjustments to minimize or eliminate blood backflow.&#160;</li>
		<li>Temporarily mono-occlude the descending aorta proximal to the catheter insertion point, at the point of separation of the descending aorta and vena cava.</li>
		<li>Pierce the upper wall of the descending aorta using a twisted 21-G needle, as demonstrated in the video, and insert the pressure catheter tip (diameter of tip 0.74 mm) of the telemetric implant. If the pressure catheter tip does not enter the aorta, guide it using a vein pick at the puncturing site.</li>
		<li>Insert the catheter tip 1.5-2 cm into the descending aorta. Clean any blood around the insertion site and apply a few drops of tissue adhesive to secure the implant and prevent bleeding. Allow 30-45 s after implant insertion for the adhesive to dry. Check for any blood leakage before proceeding forward.</li>
		<li>Anchor the implant body to the abdominal wall intraperitoneally, slightly away from the incision site, by suturing the suture rib with non-absorbable sutures to ensure stability throughout the experiment.</li>
	</ol>
	</li>
	<li>Abdominal wall and incision closure
	<ol>
		<li>Close the abdominal wall using absorbable sutures in an interrupted pattern with square knots. Close the skin using an intradermal, continuous suturing technique.</li>
		<li>Clean the incision area with hydrogen peroxide to remove any blood residue. Follow with an application of povidone-iodine solution, then apply a triple antibiotic cream containing Polymyxin B Sulfate, Bacitracin Zinc, and Neomycin Sulfate to facilitate healing.</li>
	</ol>
	</li>
	<li>Post-surgical care
	<ol>
		<li>Immediately after surgery, inject the antibiotic enrofloxacin (5 mg/kg) subcutaneously. Place the rat in a home cage with a heating pad underneath, positioned supine, until it recovers from anesthesia. 
		NOTE: Most animals recover from anesthesia immediately, but some may take 5-10 min.</li>
		<li>Once the rat is awake, fit an e-collar for 3 days around its neck to prevent biting of the abdominal sutures.</li>
		<li>For thermoregulation, keep the animal on alpha pads in a recovery cage with a water heating pad at 37-38 &#176;C underneath for at least 24-72 h. Position half of the cage on the heating pad, allowing animals to move away from the heat if needed.</li>
		<li>Administer post-operative medications subcutaneously: buprenorphine and meloxicam (twice daily for 3 days), and enrofloxacin (once daily for 5 days) to manage pain, inflammation, and infection. Provide food and water ad libitum.</li>
	</ol>
	</li>
</ol>
2. Surgical procedure for thoracic (T3) contusion injury
NOTE: The T3 contusion procedure was adapted from Squair et al.26. The total duration of the T3 contusion injury procedure is approximately 40-45 min. The materials required for the T3 contusion SCI are listed in the Table of Materials. Perform the T3 contusion at least two weeks after the telemetric implant placement. The 2-week window was optimized based on observations that most animals recover from surgical distress and return to baseline blood pressure within 7-10 days. However, some animals may take a little longer.
<ol>
	<li>Pre-surgery preparations
	<ol>
		<li>Anesthetize the rat with intraperitoneal ketamine (80 mg/kg) and xylazine (7 mg/kg). Administer buprenorphine (0.02 mg/kg), meloxicam (1 mg/kg), and 5mL of 0.9% normal saline subcutaneously prior to surgery.</li>
		<li>Shave the dorsal surface from the cervical to mid-thoracic region using an electric shaver. Clean the skin three times with alcohol prep pads, followed by application of 5% povidone-iodine solution. Use lubricating eye gel to prevent corneal dehydration.</li>
		<li>Place the rat on a heating pad with surgical underpads covered with sterile drape towels, as done during the telemetric surgical procedure.</li>
	</ol>
	</li>
	<li>Incision, blunt dissection, and laminectomy
	<ol>
		<li>Identify the T2 spinous process by its prominent dorsal spine and mark it. Make a dorsal midline incision from C7-T5 vertebral level and secure the area with muscle retractors.</li>
		<li>Perform blunt dissection using fine, small scissors and a curette through the superficial and deep paraspinal musculature. Avoid venous corona mortis around T4/T5 during dissection, as damaging it can cause animal&#39;s immediate death.</li>
		<li>Perform a T3 laminectomy to expose the T3 spinal segment.</li>
	</ol>
	</li>
	<li>Spinal cord contusion
	<ol>
		<li>Secure the animal at the T2 and T4 spinal processes using Allis forceps on the IH impactor stage.</li>
		<li>Align the impactor tip over the midline using the 3D coordinate system to ensure an accurate midline hit. Set the parameters as required (Force = 400 kdyn with 5 s dwell time).</li>
	</ol>
	</li>
	<li>Incision closure and post-surgical care
	<ol>
		<li>Suture the paraspinal muscles with absorbable sutures and seal the incision site with staples. Remove any blood residues near the incision area using hydrogen peroxide.</li>
		<li>Proceed with an application of povidone-iodine solution, then smear a triple antibiotic cream containing Polymyxin B Sulfate, Bacitracin Zinc, and Neomycin Sulfate to facilitate healing. Administer enrofloxacin (5 mg/kg) subcutaneously, immediately after the injury. Place the rat on alpha pads in recovery cages with heating pads underneath.</li>
		<li>Provide post-operative care, including buprenorphine and meloxicam (twice daily for 3 days), and enrofloxacin (once daily for 5 days). Manually express the bladder two times daily until spontaneous bladder expression occurs (Cred&#233; maneuver). Provide food and water ad libitum. 
		NOTE: Place rats on alpha pads post-surgery for at least 5 days. Provide some food pellets inside the home cage as well to ensure access during the period of restricted movement.</li>
	</ol>
	</li>
</ol>
3. Settings for recording and exporting data
NOTE: The settings for recording and exporting cardiovascular, core body temperature, animal activity parameters, pre- and post-SCI using Ponemah software (version 6.51) are mentioned.
<ol>
	<li>Data recording
	<ol>
		<li>For recording the various parameters, click on Create under the Experiment tab and label the experiment.</li>
		<li>Go to the Hardware tab, click on Edit APR Configuration, select the APR, and click on Add to move it to the available region. Then, click on Edit PhysioTel/HD MX2 Configuration in the hardware tab to select the MX-2,&#160;click on Add, and confirm that it appears in the left panel. Add implants assigned to different animals from the implant inventory on the right side to the middle and left panels. The number of implants that can be added depends on the number of receiver plates connected with the system. Click on each added implant (labeled with animal number) in the left panel and connect it to a different receiver plate. Save and exit once all connections are made.</li>
		<li>Go to the Set up tab and then choose Experiment Setup, click on Enable Page, then click on the black background. Choose the subject, add pressure in the label, change the unit to mmHg, set the low and high values, and choose a color for displaying blood pressure traces.</li>
		<li>Go to the Set up tab and then choose Animal Setup. Click on the animal number, select the gender and species, then click on Pressure to enable parameters. If heart rate needs to be displayed, click on Heart Rate. Apply channel settings to similar channels, then click OK. This opens a window with different implants arranged in vertical order.</li>
		<li>Click on All Continuous on the top to visualize the blood pressure recording traces on the screen.</li>
	</ol>
	</li>
	<li>Data exporting
	<ol>
		<li>Begin by navigating to the Experiment tab, clicking on Open, and selecting the data from the intended folder.</li>
		<li>Go to the Action tab, click on Start Review, and select the subject number, desired signal types, and time range by checking the intended outcomes. Note that the software exports up to 3GB of data at a time. The data can be derived by setting the logging rate in the actions tab, which determines how the data is segmented (in seconds, minutes, or hours).</li>
		<li>Once selections are made, click on the Experiment tab, then choose Save Marked Sections followed by Save Derived Data.</li>
		<li>Finally, go to the Actions tab and click on Close Review Session to end the data export.</li>
	</ol>
	</li>
</ol>

<ol><li>Bhattacharyya, S., Sahu, S., Kaur, S., Jain, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effect+of+low+intensity+magnetic+field+stimulation+on+calcium-mediated+cytotoxicity+after+mild+spinal+cord+contusion+injury+in+rats%5BTitle%5D)+AND+%22Ann+Neurosci%22%5BJournal%5D)">Effect of low intensity magnetic field stimulation on calcium-mediated cytotoxicity after mild spinal cord contusion injury in rats.</a> Ann Neurosci. 27 (2), 49-56 (2020).</li>
<li>Hagen, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Acute+complications+of+spinal+cord+injuries%5BTitle%5D)+AND+%22World+J+Orthop%22%5BJournal%5D)">Acute complications of spinal cord injuries.</a> World J Orthop. 6 (1), 17-23 (2015).</li>
<li>Hagen, E. M., Rekand, T., Gronning, M., Faerestrand, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cardiovascular+complications+of+spinal+cord+injury%5BTitle%5D)+AND+%22Tidsskr+Nor+Laegeforen%22%5BJournal%5D)">Cardiovascular complications of spinal cord injury.</a> Tidsskr Nor Laegeforen. 132 (9), 1115-1120 (2012).</li>
<li>Kaur, S., Jain, S., Bhardwaj, R., Kumaran, S. S., Kochhar, K. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Modulation+of+the+biphasic+pattern+of+cortical+reorganization+in+spinal+cord-transected+rats+by+external+magnetic+fields%5BTitle%5D)+AND+%22J+Biosci%22%5BJournal%5D)">Modulation of the biphasic pattern of cortical reorganization in spinal cord-transected rats by external magnetic fields.</a> J Biosci. 50, 71(2025).</li>
<li>Furlan, J. C., Fehlings, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cardiovascular+complications+after+acute+spinal+cord+injury%3A+pathophysiology%2C+diagnosis%2C+and+management%5BTitle%5D)+AND+%22Neurosurg+Focus%22%5BJournal%5D)">Cardiovascular complications after acute spinal cord injury: pathophysiology, diagnosis, and management.</a> Neurosurg Focus. 25 (5), E13(2008).</li>
<li>Cragg, J. J., Noonan, V. K., Krassioukov, A., Borisoff, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cardiovascular+disease+and+spinal+cord+injury%3A+results+from+a+national+population+health+survey%5BTitle%5D)+AND+%22Neurology%22%5BJournal%5D)">Cardiovascular disease and spinal cord injury: results from a national population health survey.</a> Neurology. 81 (8), 723-728 (2013).</li>
<li>Grossmann, F., Flueck, J. L., Perret, C., Meeusen, R., Roelands, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+thermoregulatory+and+thermal+responses+of+individuals+with+a+spinal+cord+injury+during+exercise%2C+acclimation+and+by+using+cooling+strategies-A+systematic+review%5BTitle%5D)+AND+%22Front+Physiol%22%5BJournal%5D)">The thermoregulatory and thermal responses of individuals with a spinal cord injury during exercise, acclimation and by using cooling strategies-A systematic review.</a> Front Physiol. 12, 636997(2021).</li>
<li>Grigorean, V. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cardiac+dysfunctions+following+spinal+cord+injury%5BTitle%5D)+AND+%22J+Med+Life%22%5BJournal%5D)">Cardiac dysfunctions following spinal cord injury.</a> J Med Life. 2 (2), 133-145 (2009).</li>
<li>Weaver, L. C., Flemfing, J. C., Mathias, C. J., Krassioukov, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Disordered+cardiovascular+control+after+spinal+cord+injury%5BTitle%5D)+AND+%22Handb+Clin+Neurol%22%5BJournal%5D)">Disordered cardiovascular control after spinal cord injury.</a> Handb Clin Neurol. 109, 213-233 (2012).</li>
<li>Partida, E., Mironets, E., Hou, S., Tom, V. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cardiovascular+dysfunction+following+spinal+cord+injury%5BTitle%5D)+AND+%22Neural+Regen+Res%22%5BJournal%5D)">Cardiovascular dysfunction following spinal cord injury.</a> Neural Regen Res. 11 (2), 189-194 (2016).</li>
<li>Garshick, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+prospective+assessment+of+mortality+in+chronic+spinal+cord+injury%5BTitle%5D)+AND+%22Spinal+Cord%22%5BJournal%5D)">A prospective assessment of mortality in chronic spinal cord injury.</a> Spinal Cord. 43 (7), 408-416 (2005).</li>
<li>Krassioukov, A. V., Furlan, J. C., Fehlings, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Autonomic+dysreflexia+in+acute+spinal+cord+injury%3A+an+under-recognized+clinical+entity%5BTitle%5D)+AND+%22J+Neurotrauma%22%5BJournal%5D)">Autonomic dysreflexia in acute spinal cord injury: an under-recognized clinical entity.</a> J Neurotrauma. 20 (8), 707-716 (2003).</li>
<li>Eldahan, K. C., Rabchevsky, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Autonomic+dysreflexia+after+spinal+cord+injury%3A+systemic+pathophysiology+and+methods+of+management%5BTitle%5D)+AND+%22Auton+Neurosci%22%5BJournal%5D)">Autonomic dysreflexia after spinal cord injury: systemic pathophysiology and methods of management.</a> Auton Neurosci. 209, 59-70 (2018).</li>
<li>Karlsson, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Autonomic+dysreflexia%5BTitle%5D)+AND+%22Spinal+Cord%22%5BJournal%5D)">Autonomic dysreflexia.</a> Spinal Cord. 37, 383-391 (1999).</li>
<li>Canon, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Autonomic+dysreflexia+during+urodynamics+in+children+and+adolescents+with+spinal+cord+injury+or+severe+neurologic+disease%5BTitle%5D)+AND+%22J+Pediatr+Urol%22%5BJournal%5D)">Autonomic dysreflexia during urodynamics in children and adolescents with spinal cord injury or severe neurologic disease.</a> J Pediatr Urol. 11 (1), 32.e1-32.e4 (2015).</li>
<li>Lindan, R., Joiner, E., Freehafer, A. A., Hazel, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Incidence+and+clinical+features+of+autonomic+dysreflexia+in+patients+with+spinal+cord+injury%5BTitle%5D)+AND+%22Paraplegia%22%5BJournal%5D)">Incidence and clinical features of autonomic dysreflexia in patients with spinal cord injury.</a> Paraplegia. 18 (5), 285-292 (1980).</li>
<li>Ho, C. P., Krassioukov, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Autonomic+dysreflexia+and+myocardial+ischemia%5BTitle%5D)+AND+%22Spinal+Cord%22%5BJournal%5D)">Autonomic dysreflexia and myocardial ischemia.</a> Spinal Cord. 48 (9), 714-715 (2010).</li>
<li>Wan, D., Krassioukov, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Life-threatening+outcomes+associated+with+autonomic+dysreflexia%3A+A+clinical+review%5BTitle%5D)+AND+%22J+Spinal+Cord+Med%22%5BJournal%5D)">Life-threatening outcomes associated with autonomic dysreflexia: A clinical review.</a> J Spinal Cord Med. 37 (1), 2-10 (2014).</li>
<li>Kalra, D. K., Raina, A., Sohal, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Neurogenic+orthostatic+hypotension%3A+State+of+the+art+and+therapeutic+strategies%5BTitle%5D)+AND+%22Clin+Med+Insights+Cardiol%22%5BJournal%5D)">Neurogenic orthostatic hypotension: State of the art and therapeutic strategies.</a> Clin Med Insights Cardiol. 14, 1179546820953415(2020).</li>
<li>Kim, M. J., Farrell, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Orthostatic+hypotension%3A+A+practical+approach%5BTitle%5D)+AND+%22Am+Fam+Physician%22%5BJournal%5D)">Orthostatic hypotension: A practical approach.</a> Am Fam Physician. 105 (1), 39-49 (2022).</li>
<li>Braga, V. A., Prabhakar, N. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Refinement+of+telemetry+for+measuring+blood+pressure+in+conscious+rats%5BTitle%5D)+AND+%22J+Am+Assoc+Lab+Anim+Sci%22%5BJournal%5D)">Refinement of telemetry for measuring blood pressure in conscious rats.</a> J Am Assoc Lab Anim Sci. 48 (3), 268-271 (2009).</li>
<li>Chinnadurai, S. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Comparison+of+an+implantable+telemetry+device+and+an+oscillometric+monitor+for+measurement+of+blood+pressure+in+anaesthetized+and+unrestrained+green+iguanas+%28Iguana+iguana%29%5BTitle%5D)+AND+%22Vet+Anaesth+Analg%22%5BJournal%5D)">Comparison of an implantable telemetry device and an oscillometric monitor for measurement of blood pressure in anaesthetized and unrestrained green iguanas (Iguana iguana).</a> Vet Anaesth Analg. 37 (5), 434-439 (2010).</li>
<li>Harrison, D. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Tail-cuff+versus+radiotelemetry+to+measure+blood+pressure+in+mice+and+rats%5BTitle%5D)+AND+%22Hypertension%22%5BJournal%5D)">Tail-cuff versus radiotelemetry to measure blood pressure in mice and rats.</a> Hypertension. 81 (1), 3-5 (2024).</li>
<li>Rabchevsky, A. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effects+of+gabapentin+on+muscle+spasticity+and+both+induced+as+well+as+spontaneous+autonomic+dysreflexia+after+complete+spinal+cord+injury%5BTitle%5D)+AND+%22Front+Physiol%22%5BJournal%5D)">Effects of gabapentin on muscle spasticity and both induced as well as spontaneous autonomic dysreflexia after complete spinal cord injury.</a> Front Physiol. 3, 329(2012).</li>
<li>Squair, J. W., White, B. A., Bravo, G. I., Martin Ginis, K. A., Krassioukov, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+economic+burden+of+autonomic+dysreflexia+during+hospitalization+for+individuals+with+spinal+cord+injury%5BTitle%5D)+AND+%22J+Neurotrauma%22%5BJournal%5D)">The economic burden of autonomic dysreflexia during hospitalization for individuals with spinal cord injury.</a> J Neurotrauma. 33 (15), 1422-1427 (2016).</li>
<li>Squair, J. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Minocycline+reduces+the+severity+of+autonomic+dysreflexia+after+experimental+spinal+cord+injury%5BTitle%5D)+AND+%22J+Neurotrauma%22%5BJournal%5D)">Minocycline reduces the severity of autonomic dysreflexia after experimental spinal cord injury.</a> J Neurotrauma. 35 (24), 2861-2871 (2018).</li>
<li>Niemeyer, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Telemetry+for+small+animal+physiology%5BTitle%5D)+AND+%22Lab+Anim+%28NY%29%22%5BJournal%5D)">Telemetry for small animal physiology.</a> Lab Anim (NY). 45 (7), 255-257 (2016).</li>
<li>Cruz-López, E. O., Merkus, D., Danser, A. H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Blood+pressure+monitoring+through+radiotelemetry%3A+exploring+the+viability+of+its+application+in+multihoused+small+laboratory+animals%5BTitle%5D)+AND+%22Hypertension%22%5BJournal%5D)">Blood pressure monitoring through radiotelemetry: exploring the viability of its application in multihoused small laboratory animals.</a> Hypertension. 81 (5), 947-950 (2024).</li>
<li>Molcan, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Telemetric+data+collection+should+be+standard+in+modern+experimental+cardiovascular+research%5BTitle%5D)+AND+%22Physiol+Behav%22%5BJournal%5D)">Telemetric data collection should be standard in modern experimental cardiovascular research.</a> Physiol Behav. 242, 113620(2021).</li>
<li>Wang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Artificial+intelligence+measuring+the+aortic+diameter+assist+in+identifying+adverse+blood+pressure+status+including+masked+hypertension%5BTitle%5D)+AND+%22Postgrad+Med%22%5BJournal%5D)">Artificial intelligence measuring the aortic diameter assist in identifying adverse blood pressure status including masked hypertension.</a> Postgrad Med. 134 (1), 111-121 (2022).</li>
<li>DePaolo, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Relationship+between+ascending+thoracic+aortic+diameter+and+blood+pressure%3A+a+Mendelian+randomization+study%5BTitle%5D)+AND+%22Arterioscl+Throm+Vas%22%5BJournal%5D)">Relationship between ascending thoracic aortic diameter and blood pressure: a Mendelian randomization study.</a> Arterioscl Throm Vas. 43 (2), 359-366 (2023).</li>
<li>Hou, S., Blesch, A., Lu, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+radio-telemetric+system+to+monitor+cardiovascular+function+in+rats+with+spinal+cord+transection+and+embryonic+neural+stem+cell+grafts%5BTitle%5D)+AND+%22J+Vis+Exp%22%5BJournal%5D)">A radio-telemetric system to monitor cardiovascular function in rats with spinal cord transection and embryonic neural stem cell grafts.</a> J Vis Exp. (92), e51914(2014).</li>
<li>Marie, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Carotid+versus+femoral+access+for+transcatheter+aortic+valve+replacement%3A+comparable+results+in+the+current+era%5BTitle%5D)+AND+%22Eur+J+Cardiothorac+Surg%22%5BJournal%5D)">Carotid versus femoral access for transcatheter aortic valve replacement: comparable results in the current era.</a> Eur J Cardiothorac Surg. 60 (4), 874-879 (2021).</li>
<li>Gaudet, A. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Spinal+cord+injury+in+rats+disrupts+the+circadian+system%5BTitle%5D)+AND+%22eNeuro%22%5BJournal%5D)">Spinal cord injury in rats disrupts the circadian system.</a> eNeuro. 5 (6), (2018).</li>
</ol>

The authors have nothing to disclose.

Placing a telemetric implant in the descending aorta provides a reliable method for measuring cardiovascular parameters, core body temperature, and animal activity. Telemetry offers clear advantages over non-telemetric techniques. It allows data collection from awake, freely moving animals, eliminating the confounding effects of anesthesia, which can alter blood pressure and heart rate21,27. Unlike non-telemetric methods, telemetry prevents thermal and animal restraining stress, ensuring accurate cardiovascular measurements23,28. It enables continuous monitoring of blood pressure, heart rate, core body temperature, and activity for weeks or even months, whereas non-telemetric procedures record only intermittently21,28,29. Overall, telemetric monitoring provides greater accuracy and precision than non-telemetric approaches27.
Telemetric methods diminish physical and physiological stress, preserving natural behavior and ensuring compliance with animal welfare guidelines27. Their high precision and lower variability compared with non-telemetric techniques decrease the number of animals required and increase statistical power21,23. Telemetry also offers strong translational value in drug discovery and cardiovascular research, as the data closely resemble human physiological responses28. Collectively, the telemetric approach is superior and ethically preferable to non-telemetric methods.
Telemetric implant placement in the descending aorta of rats offers several advantages for SCI research compared with placement in the carotid or femoral arteries, which serve as alternative implant sites in animal models. Being a large central vessel, the descending aorta provides stable and representative measurements of blood pressure and heart rate, critical indicators for assessing cardiovascular dysfunction after SCI30,31. Implantation at this site minimizes interference with limb blood flow and reduces the risk of ischemia and other complications often associated with peripheral artery placement30,31. It also allows continuous monitoring of basal cardiovascular parameters and autonomic dysreflexia, both crucial in SCI research24. Implanting in the femoral artery may compromise blood supply to the ipsilateral hindlimb, potentially affecting experimental outcomes and animal welfare32,33. Although technically simpler, carotid artery implantation carries risks such as stroke or neurological complications due to its proximity to the cerebral circulation, which is undesirable in studies focused on peripheral cardiovascular effects33. Therefore, implantation in the descending aorta provides a dependable site, minimizes local complications, and enhances both the experimental rigor and translational value of data collected from conscious, freely moving animals. Several common challenges are encountered while placing telemetric implants in the descending aorta.
Through trial and error, the procedure was optimized to overcome the following obstacles: (1) Abdominal inflammation: Abdominal inflammation was observed in rats at both acute and chronic stages following telemetric implant surgery. To mitigate this, a post-operative regimen consisting of the analgesic buprenorphine and anti-inflammatory meloxicam was implemented, resulting in a reduced incidence of abdominal inflammation. Previously, in each cohort, a few animals developed bloated, firm abdomens and eventually died. During implant retrieval, the abdominal cavity often contained clear fluid or, in some cases, brownish fluid with a pungent odor. This regimen reduced the rate of inflammation by approximately 70%-80% compared to animals that underwent surgery without it; (2) Extensive bleeding during dissection of the descending aorta from the vena cava: Use fine forceps (microdissection tweezers and mirror finish forceps) to gently separate the descending aorta from the vena cava using blunt dissection (hold and tear). Avoid cutting between the two using scissors or a blade, as it can cause extensive bleeding due to rupture of the underlying vasculature; (3) Insertion of telemetric implant in superficial layer: During descending aortic piercing, ensure that the needle passes through all three layers of the upper wall and not just the superficial layer. Oozing of blood after piercing indicates that all layers of the upper wall are pierced. The telemetric implant will not record properly if the pressure catheter is inserted only in the superficial layer; (4) Insertion of incorrect catheter length: Use a microscope during and/or after implant insertion to ensure the pressure catheter crosses the occlusion thread. The implant will not function properly if the inserted catheter length is incorrect; (5) Blood leakage from descending aorta: Allow 30-45 s after implant insertion for the adhesive to dry. This ensures the piercing in the descending aorta is fully sealed and not bleeding. Reseal if minor bleeding occurs due to blood backflow. Avoid pulling the implant&#39;s pressure catheter tip while suturing the implant body to the side of the abdominal wall, as this can cause bleeding; (6) Rats removing abdominal sutures: Rats may bite and remove sutures, leading to skin and internal organ damage. To reduce this, use uninterrupted sutures with a square knot for closing the abdominal wall. For skin closure, apply intradermal continuous sutures to minimize the animal&#39;s access to the sutures and knots. Apply an e-collar for 3 days postoperatively to further restrict access. Ensure that the fit is snug but not restrictive by placing an index finger between the collar and the rat&#39;s neck; (7) Hindlimb ischemia: Previously, the aorta was occluded at two locations: one at the descending aorta 0.5 cm below the renal artery, and another above the iliac bifurcation. The bi-occlusion technique helped to keep the artery taut, facilitating smoother implant placement and limiting blood backflow. However, it led to hindlimb ischemia in some animals if catheter insertion is not performed rapidly. Presently, a mono-occlusion 0.5 cm below the renal artery is performed, which effectively eliminates hindlimb ischemia in rats. With bi-occlusion, approximately 20%-30% ischemia was observed, whereas mono-occlusion completely eliminated hindlimb ischemia.
Applications 
Telemetric implants (HD-S10) are magnetically activated devices designed to record various physiological parameters in small animal models. The placement of these implants in the descending aorta is a precise and dependable method for continuous hemodynamic monitoring in unrestrained, unanesthetized, and freely moving animals. This methodology allows preclinical researchers to perform real-time assessments of various cardiovascular parameters, temperature, and animal activity in the context of disease modeling, such as SCI, drug efficacy evaluation, and diurnal changes in autonomic function parameters. Researchers can acquire comprehensive physiological data from a single telemetric implant in an animal, covering both acute and chronic timepoints, making it an efficient technique. Figure 1 highlights this telemetry application and others currently used in the laboratory.
Hemodynamic parameters, including SBP, DBP, and MAP, can be recorded over both acute and chronic periods. Monitoring the 24/7 rest-activity rhythm can serve as a reliable marker of the acute effects of SCI34. Simultaneous heart rate monitoring enables the detection of heart rate variability, including tachycardia and bradycardia. Comparing blood pressure and heart rate fluctuations pre- and post-SCI allows researchers to understand how cardiovascular physiology changes following injury. A robust daily rhythm in cardiovascular parameters, core body temperature, and activity is important for maintaining physiological homeostasis and overall health. Changes in diurnal core body temperature are also indicative of impaired thermoregulation after SCI34. It is well established that SCI is a whole-body syndrome. Therefore, incorporating telemetric-based outcomes allows researchers to collect comprehensive activity data post-SCI beyond locomotor recovery, which is typically evaluated in isolation.
However, there are certain limitations of this technique that need to be considered. The placement of a telemetric probe in the descending aorta is a complicated procedure and therefore requires microsurgical expertise. The implant can become dislodged later due to various reasons, including mishandling during bladder expression in SCI rats, infection, tissue irritation, or internal clot formation. The cardiovascular recording will be affected if any of these occur; the data should be excluded. In addition, if a rat does not recover properly, the baseline cardiovascular data may be compromised. The telemetric setup and implants are expensive and require specialized software and equipment for data acquisition. Severe SCI may possibly lead to increased mortality; therefore, careful planning of animal numbers is necessary to maintain the overall statistical power of the study.
Overall, assessing cardiovascular dysfunctions,&#160;core body temperature, and activity using telemetry after SCI, across acute and chronic periods, is critical for understanding the impact of injury on cardiovascular health, overall well-being, and for designing potential interventions.

Traumatic Spinal cord injury (SCI) impairs sensory and motor functions and disrupts cardiovascular and thermal regulation1,2,3,4. Injuries at or above the T6 level disrupt supraspinal control of autonomic function, leading to severe alterations in various cardiovascular responses, including impaired baroreceptor reflexes, blood pressure dysregulation, heart rate variability (bradycardia or tachycardia), thermodysregulation, and decreased motor activity3,5,6,7,8,9,10. These abnormalities are observed during both the acute and chronic phases of injury2,3. Due to age-related changes in demographics over the years, cardiovascular dysfunction has become one of the leading causes of mortality and long-term morbidity in individuals with SCI9,11. The acute phase of injury causes neurogenic shock, which is often characterized by hypotension and bradycardia due to sympathetic disruption9 but can also lead to hypertension in individuals with injury above T6 level12,13. During the chronic phase, these individuals often experience autonomic dysreflexia (AD) and orthostatic hypotension(OH)5. AD is a life-threatening condition defined as a sudden episodic increase in systolic blood pressure (SBP) of 20-40 mmHg above baseline14,15. Individuals may experience a range of symptoms, including a pounding headache, skin flushing, sweating, nasal congestion, piloerection, anxiety, and blurred vision13,14,16. If untreated, AD can elevate SBP up to 300 mm Hg, potentially leading to seizures, stroke, myocardial infarction, or sudden death17,18. OH is characterized by sudden reduction in blood pressure (BP) upon transitioning from a supine or seated position to standing, potentially resulting in dizziness, lightheadedness, or fainting. It is clinically defined as a sustained decrease in systolic blood pressure of at least 20 mmHg or diastolic blood pressure (DBP) of at least 10 mmHg within 3 minutes of standing19,20. Thus, the chronic phase is characterized by both hypertension and hypotension episodes in individuals with severe-high thoracic SCI. A detailed understanding of cardiovascular physiology, core body temperature fluctuations, and activity in animal models is essential for designing targeted interventions to address autonomic dysfunction during both the acute and chronic phases following SCI.
The placement of a telemetric implant in the descending aorta enables efficient recording of the impact of SCI on systolic and diastolic blood pressure, mean arterial pressure (MAP), heart rate, core body temperature, and activity in rodent models of experimental SCI. Understanding the robust and sensitive methodology for telemetric implant placement is crucial for acquiring reliable physiological data following SCI. Telemetric techniques for recording blood pressure offer several advantages over non-telemetric techniques (e.g., the tail cuff technique). The advantages include continuous and real-time monitoring, reduced stress-induced artifacts, enhanced data accuracy and reproducibility, improved animal welfare, and suitability for small or sensitive models, such as disease models, pregnant animals, and neonates21,22,23. Owing to these benefits, telemetric techniques facilitate experimental reproducibility and enhance translational relevance in SCI research by enabling the modeling of human-like autonomic and neural responses in unrestrained, freely moving animals.
The present manuscript provides a detailed, step-by-step methodology for telemetric implant placement in the descending aorta24, followed by a severe high-thoracic contusion SCI procedure25,26. It demonstrates how various cardiovascular, core body temperature, and behavioral parameters can be recorded using Ponemah software. The manuscript also outlines the challenges associated with the procedure and offers potential solutions. Additionally, it highlights the various applications of in vivo telemetry in SCI research.

<table><tbody><tr><td>Angled forceps</td><td>Dumont surgicals, Switzerland</td><td>S&amp;amp;T 00571</td><td>Telemetric surgery</td></tr><tr><td>Absorbable sutures (5-0), monofilament</td><td>Covidien LLC, USA</td><td>UM-213</td><td>Telemetric and T3 surgery</td></tr><tr><td>Actril cold sterilant</td><td>Minntech renal systems, USA</td><td>P/N 78270-000</td><td>Telemetric surgery</td></tr><tr><td>Artificial tears</td><td>Henry Schein, USA</td><td>NDC 11695-6832-1</td><td>Telemetric and T3 surgery</td></tr><tr><td>Buprenorphine</td><td>Hospira, Inc., USA&amp;nbsp;</td><td>0409-2012-32</td><td>Telemetric and T3 surgery</td></tr><tr><td>Cotton-tip applicators</td><td>VWR North American, USA</td><td>89031-272</td><td>Telemetric and T3 surgery</td></tr><tr><td>Curette</td><td>World Precision Instruments, USA</td><td>503753</td><td>T3 surgery</td></tr><tr><td>e-collar</td><td>Henry&amp;rsquo;s Fresh and Healthy Pet food, USA</td><td>RC404 VS- medium</td><td>Telemetric surgery</td></tr><tr><td>Electrical shaver</td><td>Remington, USA&amp;nbsp;</td><td>HC-5855</td><td>Telemetric and T3 surgery</td></tr><tr><td>Enrofloxacin</td><td>Norbrook laboratories limited, UK</td><td>555529-154-01</td><td>Telemetric and T3 surgery</td></tr><tr><td>Fish (Micro- Adson) forceps</td><td>F.S.T, Germany</td><td>11006-12</td><td>Telemetric and T3 surgery</td></tr><tr><td>Gauge sponges</td><td>Dukal corporation, USA</td><td>DUK4162</td><td>Telemetric and T3 surgery</td></tr><tr><td>Haemo-Sol detergent</td><td>Haemo-Sol International, USA</td><td>026-050</td><td>Telemetric surgery</td></tr><tr><td>Halsey Needle holder</td><td>F.S.T, Germany</td><td>12500-12</td><td>Telemetric and T3 surgery</td></tr><tr><td>Heating pad</td><td>Sunbeam, USA</td><td>PN126985-L</td><td>Telemetric and T3 surgery</td></tr><tr><td>Hydrogen Peroxide (3%)</td><td>Medline Industries, Inc, USA</td><td>MDS098001ZCT</td><td>Telemetric and T3 surgery</td></tr><tr><td>Infinite Horizon, IH</td><td>Precision Systems and Instrumentation, USA</td><td>IH-0400</td><td>T3 surgery</td></tr><tr><td>Isoflurane</td><td>Animal health International, Inc., USA</td><td>78949580</td><td>Telemetric surgery</td></tr><tr><td>Ketamine</td><td>Covetrus, USA</td><td>80524</td><td>T3 surgery</td></tr><tr><td>Magnet</td><td>Data Science International, Inc., USA</td><td>N/A</td><td>Telemetric surgery</td></tr><tr><td>Meloxicam</td><td>Dechra Veternary products, USA&amp;nbsp;</td><td>17033-051-20</td><td>Telemetric and T3 surgery</td></tr><tr><td>Microdissection tweezer&amp;nbsp;</td><td>World Precision instruments, Switzerland</td><td>504515</td><td>Telemetric surgery</td></tr><tr><td>Mirror finish forceps</td><td>Dumont surgicals, Switzerland</td><td>11251-23</td><td>Telemetric surgery</td></tr><tr><td>Muscle retractor (big; 1)</td><td>F.S.T, Germany</td><td>17007-08</td><td>Telemetric surgery</td></tr><tr><td>Muscle retractors (small, 2)</td><td>Wexler Surgical, USA</td><td>TL0086.1</td><td>T3 surgery</td></tr><tr><td>Needle, 21G (bent for poking)</td><td>BD precision glide needle, Becton, Dickinson and company, USA</td><td>5296673</td><td>Telemetric surgery</td></tr><tr><td>Non-absorbable sutures (4-0) Polypropylene sutures</td><td>DEMETECH Corporation, USA</td><td>PM194013F13M</td><td>Telemetric surgery</td></tr><tr><td>Occlusion thread (silk)</td><td>Clover needlecraft, Inc, Japan</td><td>96</td><td>Telemetric surgery</td></tr><tr><td>Ponemah Software</td><td>Data Science International, Inc., USA</td><td>N/A</td><td>Telemetric surgery</td></tr><tr><td>Povidone- iodine (Betadine) (5%)</td><td>Avrio health, USA</td><td>304968-08</td><td>Telemetric and T3 surgery</td></tr><tr><td>Press and Seal</td><td>Glad, USA</td><td>CLO70441</td><td>Telemetric and T3 surgery</td></tr><tr><td>Regel-Kit</td><td>Data Science International, Inc., USA</td><td>276-0038-001</td><td>Telemetric surgery</td></tr><tr><td>Scalpel Handle</td><td>F.S.T, Germany</td><td>91003-12</td><td>Telemetric and T3 surgery</td></tr><tr><td>Scissor (small, fine)</td><td>F.S.T, Germany</td><td>14959-11</td><td>Telemetric and T3 surgery</td></tr><tr><td>Sodium chloride (0.9%)</td><td>Vetivex, USA</td><td>17033-492-50</td><td>Telemetric surgery</td></tr><tr><td>Somnoflo</td><td>Kent Scientific corp. ,USA</td><td>SF-01</td><td>Telemetric surgery</td></tr><tr><td>Staples</td><td>&amp;nbsp;Fine Science Tools, USA</td><td>12022-09</td><td>T3 surgery</td></tr><tr><td>Sterile Alcohol prep pads</td><td>Dukal corporation, USA</td><td>&amp;nbsp;65517-0002-1</td><td>Telemetric and T3 surgery</td></tr><tr><td>Sterile gloves</td><td>McKESSON, USA</td><td>20-1065N</td><td>Telemetric and T3 surgery</td></tr><tr><td>Sterile towel drapes (18&amp;rdquo;X26&amp;rdquo;)</td><td>Dynarex Corporation, USA</td><td>DYA4410</td><td>Telemetric and T3 surgery</td></tr><tr><td>Surgery under pads (17&amp;rdquo;X24&amp;rdquo;)</td><td>Dukal corporation, USA</td><td>22-415-758</td><td>Telemetric and T3 surgery</td></tr><tr><td>Surgical blade (no 11)</td><td>Integra Lifesciences Production Corporation, Japan</td><td>2029-03--01</td><td>Telemetric and T3 surgery</td></tr><tr><td>Telemetric HD-S10 implant</td><td>Data Sciences International, Inc., USA</td><td>270-0180-001X</td><td>Telemetric surgery</td></tr><tr><td>Transistor</td><td>Data Science International, Inc., USA</td><td>N/A</td><td>Telemetric surgery</td></tr><tr><td>Triple Antibiotic cream</td><td>Cosette Pharmaceuticals, Inc., USA</td><td>29-62231CPLNC1</td><td>Telemetric surgery</td></tr><tr><td>Vein pick</td><td>Sai infusion technologies, India</td><td>VP-10</td><td>Telemetric surgery</td></tr><tr><td>Vet bond</td><td>3M Animal Care Products, USA</td><td>34-8720-6521-3</td><td>Telemetric surgery</td></tr><tr><td>Water heating pumps</td><td>C2Dx TP700 T</td><td>CESS-95009-00</td><td>Telemetric and T3 surgery</td></tr><tr><td>Xylazine</td><td>Covetrus, USA&amp;nbsp;</td><td>61035</td><td>T3 surgery</td></tr></tbody></table>

in vivo telemetry to record long-term cardiovascular parameters, temperature, and activity in spinal cord injury rat models

In Vivo Telemetry to Record Long-Term Cardiovascular Parameters, Temperature, and Activity in Spinal Cord Injury Rat Models

Higher-level spinal cord injury (SCI) above thoracic level 6 (T6) disrupts autonomic function and contributes to secondary complications, including fluctuations in blood pressure, heart rate, and temperature. In rats, the placement of telemetric implants in the descending aorta offers a robust methodology for assessing various cardiovascular parameters, such as systolic and diastolic pressure, mean arterial pressure, and heart rate. Core body temperature and animal activity can also be recorded following telemetric implant placement. A rat with a telemetric implant is kept on the receiver plate connected to a computer system for recording various parameters. Continuous long-term recordings at defined time intervals allow for the quantification of injury-induced physiological disruptions, including day-night variations in cardiovascular function. Comparing pre-injury (baseline) and post-injury recordings enables researchers to assess the impact of SCI on these physiological metrics. This methodology paper outlines a detailed, step-by-step procedure for telemetric implant placement in the descending aorta (using mono-occlusion of the artery) of the rat, as well as continuous telemetry recording following severe-high thoracic (T3) SCI. We discuss the challenges typically encountered while performing this procedure, as well as a dedicated troubleshooting section. The data acquisition process using Ponemah software and its various applications are also discussed. Rats display SCI-associated cardiovascular, temperature, and activity abnormalities, and telemetric implants are effective devices for studying these post-injury complications and evaluating potential treatments.

The placement of a telemetric implant in the descending aorta allows measurement of autonomic dysreflexia and various cardiovascular parameters, including systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate (HR), pre- and post-SCI. The implant also measures core body temperature and activity. Comparing pre-injury and post-injury data reveals how cardiovascular outcomes, temperature, and activity are affected after SCI. Figure 1 presents the experimental design (Figure 1A-C) and representative outcomes, including autonomic dysreflexia (Figure 1D), cardiovascular parameters, including systolic blood pressure (SBP; Figure 1E (i)), diastolic blood pressure (DBP; Figure 1E (ii)), mean arterial pressure (MAP; Figure 1E (iii)), and heart rate (HR; Figure 1E (iv)), core body temperature (Figure 1E (v)), and animal activity (Figure 1E (vi)), pre- and post-spinal cord injury (Figure 1E). To minimize animal use, the data in Figure 1 were taken from an ongoing study involving female rats; however, the same procedure can be applied to male rats.
The representative graph in Figure 1D shows systolic blood pressure 1 min before the stimulus, during the stimulus, and 1 min after stimulus application in rats with T3 contusion injury after 8 weeks post-SCI using colorectal distension (CRD). CRD utilizes insertion of a balloon catheter into the rat's anus to stimulate the rectum24. The balloon is inflated once the baseline stabilizes, and the stimulus is applied for 1 min. An increase of at least 20 mm Hg SBP during stimulation over baseline SBP (prior to the stimulation) shows development of AD in the chronic phase of injury (8 weeks).
The graphs in Figure 1E compare recordings taken 48 h before T3 contusion injury and during the first two days post-injury (48 h after injury). After SCI, graphs show elevated blood pressure indicated by increased SBP, DBP, and MAP (Figure 1E (i), (ii), (iii)). Post-SCI results showed increased heart rate fluctuations (Figure 1E (iv)), irregularities in core body temperature (Figure 1E (v)), and reduced activity (Figure 1E (vi)). Additionally, SCI disrupted day-night rhythms in SBP, DBP, MAP, HR, core body temperature, and activity.
<img alt="Telemetric implant placement, contusion injury, telemetric recording; SBP trace, SCI study graphs." class="xfigimg" src="/files/ftp_upload/69714/69714fig1v5.jpg" data-altupdatedat="1779163243000" data-alt="Figure 1"> 
Figure 1: Schematic of telemetry implant placement and applications following a severe-high thoracic (T3) contusion injury. Insertion of an in vivo telemetric implant into the descending aorta of a rat (A), followed by severe high thoracic (T3) contusion injury using an IH impactor (Force = 400 kdyn with 5-s dwell time) 2 weeks later (B). Representative setup of telemetric recording using a computerized monitoring system with Ponemah software (C). Representative trace (data acquired with a logging rate of 2 s) of female rats showing autonomic dysreflexia (AD) 8 weeks after spinal cord injury (SCI). The green dotted line indicates a 1 min colorectal distension (CRD) stimulus (D), and a representative hourly mean for 48 h. i. systolic blood pressure (SBP), ii. diastolic blood pressure (DBP), iii. mean arterial pressure (MAP), iv. heart rate (HR), v. core body temperature (core body temp), and vi. activity pre- and post-SCI (E). The unshaded and shaded regions represent 12-h light and 12-h dark cycles, respectively. "0" indicates lights on, and "12" indicates lights off. The error bars represent mean ± SEM (n = 3). <a href="https://www.jove.com/files/ftp_upload/69714/69714fig1v5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

This article presents a step-by-step protocol for the placement of an in vivo telemetric implant in the descending aorta of rats, allowing continuous and long-term monitoring of cardiovascular parameters, core body temperature, and animal activity before and after severe high-thoracic spinal cord injury.

Higher-level spinal cord injury (SCI) above thoracic level 6 (T6) disrupts autonomic function and contributes to secondary complications, including ...

The scope of my research is to optimize telemetric implant surgery for long-term recording of physiological parameters in spinal contused rats. The most recent development in our field includes characterizing acute, chronic, progressive, cardiovascular, temperature activity changes after spinal cord injury. To begin, using a syringe, fill the pressure catheter tip of a telemetric implant with biocompatible gel.After sterilizing the implants by sequentially immersing them for 24 hours each in detergent, cold sterilant and 0.9%sodium chloride, keep them submerged in 0.9%sodium chloride. Cover a heating pad with surgical underpads followed by sterile drape towels to maintain a sterile field. Set the heating pad to 37 to 38 degrees Celsius.To an anesthetized rat, subcutaneously administer buprenorphine, meloxicam and five milliliters of 0.9%normal saline, then apply lubricating gel to its eyes. Shave the abdominal area from one centimeter above the urethral orifice to the mid-abdomen using an electric shaver. Disinfect the exposed skin.Then place a press-and-seal barrier and cut an opening to expose the surgical site. After confirming the depth of anesthesia via toe pinch, make a 4.5-to-five-centimeter midline skin incision from above the urethral orifice and perform an abdominal incision. Secure the visceral organs with saline-soaked, 16-ply gauze sponges and metal retractors.Using two fine forceps, gently separate fat bodies to expose the descending aorta and vena cava. Hold the fat bodies with one forceps and use the other to dissect. Perform blunt dissection approximately 0.5 centimeters below the renal artery to separate the descending aorta from the vena cava.Further separate the aorta from underlying fat to create space for angled forceps insertion. Insert angled forceps under the descending aorta through the dissected space. Tear the connective tissue between the aorta and vena cava using forceps.Then pass a sterile 4-0 silk thread underneath the descending aorta and secure both ends with a hemostat. Temporarily mono-occlude the descending aorta proximal to the catheter insertion point. Remove the implant from the sodium chloride and inspect the pressure catheter tip for air bubbles or gaps.After turning on the implant using a magnet and radio, add gel if needed before insertion. Have another experimenter hold the hemostat at about a 45-degree angle and make adjustments to minimize or eliminate blood backflow. Pierce the upper wall of the descending aorta using a twisted 21-gauge needle and insert the pressure catheter tip 1.5 to two centimeters into the descending aorta.Use a vein pick to guide the catheter if needed, and loosen the occlusion thread to advance the catheter. Clean the surrounding blood and apply tissue adhesive to secure the implant. Allow 30 to 45 seconds for the adhesive to dry, then check for blood leakage.Cut and remove occlusion thread using fine scissors and forceps. Confirm the implant status via radio telemetry. Then remove the retractor and gauze, and anchor the implant to the body while intraperitoneally using non-absorbable sutures.Next, close the abdominal wall using absorbable sutures in an interrupted pattern, and close the skin using an intradermal continuous technique. Clean the incision with hydrogen peroxide, followed by povidone iodine. Apply triple antibiotic cream to the incision site and follow the post-surgical care.Perform spinal cord injury two weeks later using IH Impactor device. Then transfer the injured rats onto telemetric plates in a cage for data acquisition. To begin data recording, launch the Ponemah software.Click Create under the Experiment tab and label the experiment. Under the Hardware tab, click on Edit APR Configuration. Then choose the APR and click on Add to move to the available region.Now, Press Edit PhysioTel HD MX2 Configuration in the Hardware tab to select the MX2, then click on Add and confirm that it appears in the left panel. Add implants assigned to different animals from the implant inventory on the right side to the middle and left panels. Click on each implant and connect it to a different receiver plate, then save and exit once all connections are made.Now, navigate to the Setup tab, then press Experimental Setup and click on Enable Page. Choose the black background, then select the subject before adding the pressure in the label and changing the unit to millimeters of mercury. Set the low and high values, and choose a color for displaying blood pressure traces.Go to the Setup tab again and choose Subject Setup. Click on the animal number, select the gender and species, and click on Pressure to enable parameters. If heart rate needs to be displayed, click on Heart Rate.Click Apply Channel Settings to Similar Channels if connecting more than one implant, then click OK.Next, click on Start All Continuous at the top of the screen to visualize blood pressure recording traces. For data exporting, go to the Experiment tab. Click on Open, and select the data from the intended folder.Navigate to the Action tab. Click on Start Review, and select the subject number, desired signal types and time range. Set the logging rate to determine how the data are segmented in seconds, minutes, or hours.Once selections are complete, go to the Experiment tab and choose Save Marked Sections, followed by Save Derived Data. Finally, go to the Actions tab and click on Close Review Session to end the data export. Eight weeks after spinal cord injury, colorectal distension induced a minimum increase of 20 millimeters of mercury in systolic blood pressure during one-minute stimulation compared with baseline, demonstrating development of autonomic dysreflexia.Systolic blood pressure, diastolic blood pressure and mean arterial pressure were elevated one to two days post-spinal cord injury compared with pre-injury recordings. Heart rate showed increased fluctuations following spinal cord injury compared with pre-injury recordings. Core body temperature regulation was disrupted during the first two days after spinal cord injury, and animal activity was reduced substantially following spinal cord injury compared with pre-injury activity.The advantage of our protocol is minimizing the procedural challenges, improving survival, and enabling continuous recording in freely moving, awake animals. Our findings will advance research by providing an in-depth understanding of autonomic changes during the acute and chronic phases of spinal cord injury. Our results pave the way for new questions by addressing key gaps and providing a foundation for deeper insight into autonomic dysfunction after spinal cord injury.

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Research

JoVE Journal

Biology

A surgical technique for implantation of commercially available telemetry transmitters used for continuous measurement of biopotential (one-lead ECG), heart rate, core body temperature and locomotor activity in freely moving mice is shown. Recommendations and protocols for post-operative care and pain relief, improving recovery, well being and survival rate are also presented.

Implantation of Radiotelemetry Transmitters Yielding Data on ECG, Heart Rate, Core Body Temperature and Activity in Free-moving Laboratory Mice

This video describes the in vivo intracellular recording of rat motoneurons under trans-spinal direct current stimulation. The protocol describes how to measure membrane properties and record the rhythmic firing of motoneurons before, during, and after anodal or cathodal polarization of the spinal cord.

Trans-Spinal Direct Current Stimulation of a Rat&#39;s Spinal Motoneuron

We present a protocol for using a radio-telemetric system to record cardiovascular parameters in T4 spinal cord transected rats eight weeks after embryonic brainstem neural stem cell grafting into the lesion site. Telemetry is an advanced technique to accurately evaluate cardiovascular function in conscious freely moving spinal cord injured rats.

A Radio-telemetric System to Monitor Cardiovascular Function in Rats with Spinal Cord Transection and Embryonic Neural Stem Cell Grafts

The catheter of a telemetry device is implanted into the abdominal aorta in order to continuously collect beat-by-beat hemodynamic data from animals pre and post-high thoracic spinal cord transection. A novel JAVA software was employed to analyze hemodynamic parameters as well as frequency and intensity of spontaneous episodes of autonomic dysreflexia.

Development of an Algorithm to Perform a Comprehensive Study of Autonomic Dysreflexia in Animals with High Spinal Cord Injury Using a Telemetry Device

We introduce an in vivo imaging method using two different fluorescent dyes to track dynamic spinal vascular changes following a contusive spinal cord injury in adult Sprague-Dawley rats.

An In Vivo Duo-color Method for Imaging Vascular Dynamics Following Contusive Spinal Cord Injury

This protocol demonstrates our model of activity-based locomotor treadmill training for rats with spinal cord injury (SCI). Included is both quadrupedal and forelimb-only groups, in addition to two distinct types of non-trained control groups. Investigators are able to assess training effects on SCI rats using this protocol.

Activity-based Training on a Treadmill with Spinal Cord Injured Wistar Rats

The rat thoracic spinal hemisection is a valuable and reproducible model of unilateral spinal cord injury to investigate the neural mechanisms of locomotor recovery and treatment efficacy. This article includes a detailed step-by-step guide to perform the hemisection procedure and to assess locomotor performance in an open-field arena.

Thoracic Spinal Cord Hemisection Surgery and Open-Field Locomotor Assessment in the Rat

This protocol describes in vivo intracellular recording of rat lumbar motoneurons with simultaneous trans-spinal direct current stimulation. The method enables us to measure membrane properties and to record rhythmic firing of motoneurons before, during and after anodal or cathodal polarization of the spinal cord.

In Vivo Intracellular Recording of Type-Identified Rat Spinal Motoneurons During Trans-Spinal Direct Current Stimulation

Electrocardiogram (ECG) is the key variable to understanding cardiac electrophysiology. Physical exercise has beneficial effects but may also be harmful in the context of cardiovascular diseases. This manuscript provides a method of recording real-time ECG during exercise, which can serve to investigate its effects on cardiac electrophysiology in mice.

Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice

We describe a protocol for spinal multichannel extracellular recording alongside cardiac function recording and analyzing the cardiac-locked spinal dorsal horn neurons. This method offers a temporally synchronized framework for studying spinal mechanisms underlying thoracic visceral functional changes induced by acupuncture.

Studying the Coding Profiles of Somatic Stimulation on Cardiac-locked Neuronal Responses in the Rat Spinal Dorsal Horn

This protocol establishes a rat hindlimb kinematic evaluation pipeline using a markerless treadmill test with deep learning-driven multi-joint trajectory auto-labeling, which enables reproducible motion quantification.

Deep-Learning Based Multi-Joint Synchronous Tracking for Objective Quantification of Hindlimb Locomotor Kinematics in Rats

Learn telemetric implant surgery for long-term cardiovascular, temperature, and activity monitoring in spinal cord injury rat models. This protocol enables continuous physiological recording in freely moving animals.

In Vivo Telemetry to Record Long-Term Cardiovascular Parameters, Temperature, and Activity in Spinal Cord Injury Rat Models

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