Dynamic Continuous Blood Extraction from Rat Heart via Noninvasive Microdialysis Technique

Our dynamic continuous blood collection technique from a rat heart is very important for analyzing the blood components, contributing to understanding cardiovascular disease and their related disease. Compared with traditional sampling methods, this technique has the advantages of in vivo, real-time, dynamic, and is non-invasive, with no biological micro moleculars and titre sample pre-process for a foreign test. This technique is not just applicable to cardiovascular diseases, but also should work for disease diagnosis and treatment by detecting blood biomarkers combined with high phase liquid chromatography and mass spectrometry.

This method can be used to investigate cardiovascular diseases such as myocardial infarction, apnea and atherosclerosis. In addition, it also applies to cardiogenic pulmonary edema and pulmonary and cerebral embolism. After doing the experimental preparation, attach the inlet of the dialysis unit probe with the syringe needle, the tubing adapter, and the FEP tubing.

Check the patency of the microdialysis piping system by perfusing anticoagulant citrate dextrose solution into the piping system. Make an incision to expose the right jugular vein by blunt dissection of soft tissue and perivascular fascia. Using a 4-0 surgical suture, make a detachable slip knot in the right jugular vein at the distal end of the heart to block the blood flow temporarily.

Then make an incision in the right jugular vein near the heart. Insert a needle-shaped catheter stylet into the right jugular vein toward the proximal end of the rat heart. Insert the blood microdialysis probe in a catheter and implant the probe with ophthalmic forceps along the oblique incision of the catheter stylet.

Remove the guided catheter stylet and fully immerse the semipermeable membrane of the probe in the right jugular vein. Unravel the detachable slip knot at the distal end of the heart to restore blood flow in the right jugular vein. Then use 4-0 surgical sutures to ligate the probe with the right jugular vein.

Place the awake rat in a free-moving tank and connect the probe to the microdialysis system. Then irrigate the anticoagulant citrate dextrose solution at a rate of two microliters per minute for one hour to equilibrate the probe dialysis membrane. Collect microdialysis blood samples and temporarily keep them in a four degree Celsius fractional container.

To reconfirm that the probe is in the right jugular vein, dissect the rat. Remove the microdialysis probe from the right jugular vein and put it into ultrapure water. Connect the probe to the pipeline and rinse overnight with ultrapure water to thoroughly wash out the residual salt in the pipe and probe.

The normal blood samples appeared bright red while potential blood clots were observed in hypoxic samples. Samples obtained through the blood microdialysis technique were colorless, clear and transparent. To avoid the membrane's destruction and the probe of sliding or displacement, we should pay attention when we are placing and immersing the probe in the rat jugular vein.

The blood samples obtained through the microdialysis technique can be used to analyze the biomarkers of different diseases and the blood distribution of drugs and rare metabolites.