We describe the protocol to perform a cardiac stress test induced by dobutamine and monitored by cardiac catheterization in normal mice. Also we show its application to unmask subclinical cardiac disease in high fat diet-induced obese mice.
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Method Article
Cardiac Stress Test Induced by Dobutamine and Monitored by Cardiac Catheterization in Mice
In This Article
Summary
Abstract
Dobutamine is a β-adrenergic agonist with an affinity higher for receptor expressed in the heart (β1) than for receptors expressed in the arteries (β2). When systemically administered, it increases cardiac demand. Thus, dobutamine unmasks abnormal rhythm or ischemic areas potentially at risk of infarction.
Monitoring of heart function during a cardiac stress test can be performed by either ecocardiography or cardiac catheterization. The latter is an invasive but more accurate and informative technique that the former.
Cardiac stress test induced by dobutamine and monitored by cardiac catheterization accomplished as described here allows, in a single experiment, the measurement of the following hemodynamic parameters: heart rate (HR), systolic pressure, diastolic pressure, end-diastolic pressure, maximal positive pressure development (dP/dtmax) and maximal negative pressure development (dP/dtmin), at baseline conditions and under increasing doses of dobutamine.
As expected, in normal mice we observed a dobutamine dose-related increase in HR, dP/dtmax and dP/dtmin. Moreover, at the highest dose tested (12 ng/g/min) the cardiac decompensation of high fat diet-induced obese mice was unmasked.
Protocol
Protocol was approved by the Ethic Committee of Facultad de Medicina Clinica Alemana-Universidad del Desarrollo.
I. Preparing Dobutamine Infusion
- Dissolve 10 mg of dobutamine in 20 ml of sterile distillated water, in order to obtain a stock solution of 500 μg/ml dobutamine. Aliquot and store at -20 °C. This solution can be used at least for 3 months.
- Thaw an aliquot of dobutamine stock solution at room temperature.
- Dilute dobutamine stock solution in sterile 0.9% NaCl, in order to obtain dobutamine working solution, which concentration is calculated using the formula: dobutamine (μg/ml) = bo....
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Results
The arterial pressure signal is defined by systolic and diastolic pressure. When the pressure sensor is inside the left ventricle, its pressure (LVP) waveform is characterized by a drop to zero of the diastolic pressure and the appearance of the left atrial contraction before ventricle contraction (Figure 1). At baseline condition, ketamine-xylazine anesthetized normal mice had HR of 280 ± 24, Pmax of 107 ± 8, Pmin of 5 ± 1, EDP of 14 ± 2, dP/dtmax of 6081 ± 365 and dP/dt.......
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Discussion
Cardiac stress test induced by dobutamine and monitored by cardiac catheterization is laborious. Nonetheless, following the protocol here describe and with a short time of training, it is possible to assess six hemodynamic parameters in a single experiment that last approximately one hour.
The critical steps of the protocol here presented are the cannulations of blood vessels. Regarding the cannulation of carotid artery, the incision performed should be deep enough to break the three tissue la.......
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Disclosures
No conflicts of interest declared.
Acknowledgements
We thank Dr. Helio Salgado, Renata Lataro and Mauro de Oliveira, School of Medicine of Ribeirão Preto, University of Sao Paulo and Dr. Ben Janssen, Cardiovascular Research Institute Maastricht, Maastricht University, for generous assistance during the set up process.
This work was supported by FONDECYT grant N° 11090114 to S.D.C.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| Reagents | |||
| PE-50/10 | Warner Instruments | 64-0752 | |
| Silk thread 6/0 HR17 | Tagum | SN0713K | |
| Xylacin 20 mg/ml | Laboratorio Centrovet | ||
| Ketamine 100 mg/ml | Drag Pharma | ||
| Sodium chloride 0.9% | Lab Sanderson S.A. | ||
| Dobutamine hydrochloride | Sigma-Aldrich | D0676 | |
| Syringe U-100 Insulin 29G x ½" | Terumo Medical Co. | ||
| Forceps Dissecting Micro 11.5 cm Style 7 | Lawton Medizintechnik | 09-0959 | |
| Graefe Forceps Cvd 0.7mm 7cm | Lawton Medizintechnik | 62-0263 | |
| Clamps Dieffenbach bulldog Cl Str 38 mm | Lawton Medizintechnik | 60-010 | |
| Vannas Scissors 8 cm Str Fh | Lawton Medizintechnik | 63-1400 | |
| Equipment | |||
| SPR-671 MiKro-Tip Pressure catheter | Millar instruments | 840-6719 | |
| PCU-2000 Pressure Control Unit | Millar instruments | 880-0129 | |
| PowerLab 4/30 | ADinstruments Pty Ltd. | ML866 | |
| LabChartPro 7 | ADinstruments Pty Ltd. | MLU260/7 | |
| Legato200 Infusion Pump | KdScientific | KD-KDS210P | |
| TCAT-2LV Temperature controller and isothermal heating plate | PhysiTemp instruments Inc. | ||
| Medical Oxygen supply | Indura | ||
| Rectal probe | ADinstruments Pty Ltd. | MLT1404 | |
| Trinocular microscope, axial illumination | LW Scientific | Z2B-TRI-ETNE, ILP-1502-LTS1, ILP-1502-DGGF |
References
- Hart, C. Y., Burnett, J. C., Redfield, M. M. Effects of avertin versus xylazine-ketamine anesthesia on cardiac function in normal mice. Am. J. Physiol. Heart Circ. Physiol. 281, H1938-H1945 (2001).
- Janssen, B. J., et al.
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