AJP - Heart and Circulatory Physiology, Vol 244, Issue 3 444-H448, Copyright © 1983 by American Physiological Society
Effect of caloric restriction on cardiac reactivity and beta-adrenoceptor concentration
D. L. Crandall, F. M. Lai, F. J. Huggins, T. K. Tanikella and P. Cervoni
The effect of a 21-day program of caloric restriction on cardiac reactivity
and beta-adrenoceptor number was investigated in male Sprague-Dawley rats.
Rats on the restricted diet (Restricted) exhibited significant decreases in
body weight, epididymal fat pad, and retroperitoneal fat pad weight as well
as the percent of body fat represented by these adipose tissue depots when
compared with rats fed ad libitum (Fed). Fed rats exhibited significantly
increased total heart weight and total heart protein, but the percent
cardiac protein and ratio of heart weight to body weight were similar in
Fed and Restricted rats. Isolated atria from Fed and Restricted rats
developed similar chronotropic and inotropic responses over a range of
isoproterenol concentrations. Although total beta-adrenoceptor number
(fmol/heart) was greater in Fed rats, the concentration of
beta-adrenoceptors (fmol/mg protein) was remarkably similar regardless of
the dietary regimen. Therefore, despite significant decreases in body
weight, body fat, and heart weight, the myocardium of Restricted rats
maintained the capability of responding to isoproterenol as that of Fed
rats, the mechanism of which is at least partially mediated through
maintenance of beta-adrenoceptor concentration.
