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In vitro Assessment of Myocardial Protection following Hypothermia-Preconditioning in a Human Cardiac Myocytes Model
Published on: October 27, 2020
Changes in cardiovascular beta-adrenoceptor responses during hypothermia.
Young-Soo Han1, Torkjel Tveita, Timofei V Kondratiev
1Department of Physiology & Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
Cryobiology
|October 7, 2008
Summary
Cardiovascular beta-adrenergic responses are significantly diminished during hypothermia. Isoproterenol (Iso) infusion failed to elicit normal heart rate and cardiac output changes in cooled rats, indicating reduced beta-adrenoceptor function.
Area of Science:
- Cardiovascular Physiology
- Pharmacology
- Hypothermia Research
Background:
- Beta-adrenergic stimulation typically enhances heart rate and contractility.
- Hypothermia is known to alter physiological responses.
- The effect of hypothermia on beta-adrenergic cardiovascular function requires further investigation.
Purpose of the Study:
- To determine cardiovascular beta-adrenergic responses during induced hypothermia.
- To assess the impact of core hypothermia on isoproterenol's effects on hemodynamics.
Main Methods:
- Rats were instrumented for hemodynamic measurements (MAP, LV pressure-volume).
- Core temperature was manipulated (37°C to 24°C and rewarming) using heat exchangers.
- Isoproterenol (Iso) was infused intravenously at varying doses during cooling and rewarming.
Main Results:
- At normothermia, Iso increased heart rate, stroke volume, cardiac output, and LV dP/dt(max) dose-dependently.
- During hypothermia (24°C), Iso infusion did not produce dose-dependent changes in hemodynamic variables.
- Rewarming revealed altered baseline hemodynamics compared to pre-hypothermia.
Conclusions:
- Cardiovascular responses mediated by beta-adrenoceptors are significantly diminished during core hypothermia.
- Hypothermia impairs the heart's ability to respond to beta-adrenergic stimulation.
- These findings have implications for understanding cardiovascular function in cold conditions.
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