Deep Hypothermia Inverts the Inotropic Effect of Isoproterenol in the Rat Myocardium

IF 4.033 Q4 Biochemistry, Genetics and Molecular Biology
C. V. Samodurova, F. V. Turin, A. S. Averin
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Abstract

The effects of the β-adrenergic receptor agonist isoproterenol on the contractile activity of the papillary muscle of the rat heart right ventricle were studied both at a temperature close to physiological (30°C) and under conditions of deep hypothermia (10°C). Isoproterenol had a pronounced positive inotropic effect at 30°C, the contraction force increased from 1.2 ± 0.1 mN in the control to 2.4 ± 0.4 mN after the addition of the agonist and there was a significant acceleration of the time parameters of contraction, that is, the time to reach the maximum contraction decreased from 101 ± 6 ms to 85 ± 4 ms; the relaxation time decreased by 50% from 55 ± 3 ms to 36 ± 1 ms. Under hypothermic conditions, isoproterenol caused a powerful negative inotropic effect, reducing the contraction force from 2.2 ± 0.4 mN to 1.2 ± 0.4 mN. The tendency to accelerate contraction persisted as at 30°C: the time to reach the maximum contraction decreased from 717 ± 52 ms to 624 ± 50 ms, and the relaxation time decreased by 50% from 667 ± 86 ms to 450 ± 40 ms. Thus, under conditions of deep hypothermia at 10°C, the direction of the inotropic response to isoproterenol changed from positive to negative, while the lusitropic effect remained negative.

Abstract Image

Abstract Image

深度低温会削弱异丙肾上腺素对大鼠心肌的肌力作用
摘要 研究了β-肾上腺素能受体激动剂异丙肾上腺素在接近生理温度(30℃)和深度低温(10℃)条件下对大鼠心脏右心室乳头肌收缩活动的影响。在 30°C 时,异丙肾上腺素具有明显的正性肌力作用,加入激动剂后,收缩力从对照组的 1.2 ± 0.1 mN 增加到 2.4 ± 0.4 mN,收缩的时间参数显著加快,即达到最大收缩力的时间从 101 ± 6 ms 减少到 85 ± 4 ms;松弛时间减少了 50%,从 55 ± 3 ms 减少到 36 ± 1 ms。在低体温条件下,异丙肾上腺素产生了强大的负性肌力作用,使收缩力从 2.2 ± 0.4 mN 降至 1.2 ± 0.4 mN。与 30°C 时一样,加速收缩的趋势依然存在:达到最大收缩力的时间从 717 ± 52 毫秒减少到 624 ± 50 毫秒,松弛时间减少了 50%,从 667 ± 86 毫秒减少到 450 ± 40 毫秒。因此,在10°C深度低温条件下,异丙托肾上腺素的肌力反应方向由正转负,而肌松效应仍为负。
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来源期刊
Biophysics
Biophysics Biochemistry, Genetics and Molecular Biology-Biophysics
CiteScore
1.20
自引率
0.00%
发文量
67
期刊介绍: Biophysics is a multidisciplinary international peer reviewed journal that covers a wide scope of problems related to the main physical mechanisms of processes taking place at different organization levels in biosystems. It includes structure and dynamics of macromolecules, cells and tissues; the influence of environment; energy transformation and transfer; thermodynamics; biological motility; population dynamics and cell differentiation modeling; biomechanics and tissue rheology; nonlinear phenomena, mathematical and cybernetics modeling of complex systems; and computational biology. The journal publishes short communications devoted and review articles.
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