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Effect of Aging on the Negative Chronotropic and Anti-β-Adrenergic Actions of Adenosine in the Rat Heart
Journal article   Open access   Peer reviewed

Effect of Aging on the Negative Chronotropic and Anti-β-Adrenergic Actions of Adenosine in the Rat Heart

Jiang Xu, Feng Gao, Xin Ma, Erhe Gao, Eitan Friedman, David Snyder, Joel Horwitz and Amir Pelleg
Journal of cardiovascular pharmacology, v 34(6), pp 904-912
Dec 1999
PMID: 10598137
url
https://doi.org/10.1097/00005344-199912000-00020View
Published, Version of Record (VoR)Maybe Open Access (Publisher Bronze) Open

Abstract

The effect of aging on the antiadrenergic actions of adenosine was studied in vitro and in vivo by using adult (6-month-old) and old (24-month-old) male Fischer 344 rats. In anesthetized animals, adenosine (0.01-0.1 μmol/kg), given as a rapid bolus into the right atrium, exerted a negative chronotropic effect manifested by a dose-dependent transient prolongation of sinus cycle length (SCL). This effect was similar in both age groups (n = 6, each; i.e., the percentage maximal prolongation of SCL (%ΔSCL) ranged from 12 ± 2% to 63 ± 14% in the adult and from 20 ± 7% to 57 ± 15% in the old rats. In the presence of isoproterenol (0.2 μg/kg/min), the negative chronotropic action of adenosine was potentiated in the adult rats much more than in the old rats [i.e., %ΔSCL ranged from 60 ± 28% to 183 ± 48% vs. 40 ± 12% to 70 ± 13%, respectively (p < 0.05, adult vs. old)]. In the isolated perfused hearts, isoproterenol (1 μM for 1 min) exerted similar chronotropic and inotropic effects in adult (n = 9) and old hearts [n = 6; i.e., heart rate, left ventricular pressure (LVP), and LVdp/dt increased by 56 ± 3%, 17 ± 1%, and 37 ± 2%, and 57 ± 2%, 17 ± 1%, and 35 ± 3%, respectively, in the absence of, and by 27 ± 2%, 7 ± 1%, and 19 ± 2% and 41 ± 3%, 12 ± 1%, and 25 ± 2% in the presence of adenosine (5 μM for 1 min)]. Adenosine administration after isoproterenol caused only an insignificant increase in coronary blood flow. Finally, the adenosine attenuation of either isoproterenol- or forskolin-induced production of 3′,5′-cyclic adenosine monophosphate (cAMP) was significantly less in atrial membranes isolated from old versus adult rats (n = 6, each). It was concluded that in the old Fischer 344 rat hearts, the antiadrenergic action of adenosine is attenuated as compared with its action in adult rat hearts.

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Collaboration types
Domestic collaboration
Web of Science research areas
Cardiac & Cardiovascular Systems
Pharmacology & Pharmacy
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