{"title":"Deep Hypothermia Inverts the Inotropic Effect of Isoproterenol in the Rat Myocardium","authors":"C. V. Samodurova, F. V. Turin, A. S. Averin","doi":"10.1134/S0006350923050251","DOIUrl":null,"url":null,"abstract":"<p>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.</p>","PeriodicalId":493,"journal":{"name":"Biophysics","volume":null,"pages":null},"PeriodicalIF":4.0330,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Biophysics","FirstCategoryId":"4","ListUrlMain":"https://link.springer.com/article/10.1134/S0006350923050251","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"Biochemistry, Genetics and Molecular Biology","Score":null,"Total":0}
引用次数: 0
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.
BiophysicsBiochemistry, 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.