AJP - Heart and Circulatory Physiology, Vol 242, Issue 5 882-H889, Copyright © 1982 by American Physiological Society
Contractile behavior of rat myocardium after reversal of hypertensive hypertrophy
J. M. Capasso, J. E. Strobeck, A. Malhotra, J. Scheuer and E. H. Sonnenblick
The effects of renovascular hypertension and its reversal on the
contractile performance of papillary muscles from rats has been examined.
Hypertension of 10 wk duration caused a 48% increase in heart weight and
significant prolongations of isometric time to peak tension (TPT), time to
half relaxation, and time to peak shortening (TPS). A significant
depression in the velocity of shortening was observed in the 10-wk group.
However, muscles from hypertensive rats were still able to maintain normal
levels of peak isometric developed tension and peak shortening; this may be
due to the observed prolongation of TPT and TPS, respectively. In addition,
calcium-activated actomyosin ATPase activity was depressed in hearts of
hypertensive animals. Reversal of hypertension was studied at 20 wk after
the onset of hypertension (10 wk of hypertension followed by 10 wk of
normotension). Contractile and biochemical alterations observed in
hypertensive animals were reversed in rats undergoing this regime. Thus
reversal of a gradually applied pressure overload resulted in the
regression of mechanical and biochemical abnormalities associated with the
pressure overload myocardial hypertrophy.
