Age-Related Reduction of Beta-Adrenoceptor Sensitivity in Rat Heart Occurs by Multiple Mechanisms
作者:
Tai-Hwang M. Fan,
Shailesh P. Banerjee,
期刊:
Gerontology
(Karger Available online 1985)
卷期:
Volume 31,
issue 6
页码: 373-380
ISSN:0304-324X
年代: 1985
DOI:10.1159/000212726
出版商: S. Karger AG
关键词: Adenylate cyclase;Rat myocardium;β-Adrenoceptor;Forskolin;Isoproterenol
数据来源: Karger
摘要:
Myocardial responsiveness to catecholamines was evaluated by measuring isoproterenol-stimulated adenylate cyclase activities in myocardial particulate fractions from Fischer 344 rats of 3, 12, and 24 months of age. Dose-response curves of isoproterenol revealed a progressive increase in the activation constant (Kact) with advancing age. In addition, the maximal velocity (Vmax) for 12- and 24-month-old groups was about. 20–25% lower than for the 3-month-old group. Analysis of receptor-binding data and nonreceptor-mediated enzyme activities suggests that the age-related decrease in Vmax for isoproterenol may result from a loss of myocardial β-receptors, whereas the increase in Kact is probably due to a deficit in the postreceptor components of the receptor-cyclase compl
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