AJP - Heart and Circulatory Physiology, Vol 261, Issue 6 1802-H1810, Copyright © 1991 by American Physiological Society
Coronary artery narrowing in rats: mechanical alterations of left and right myocardium
J. M. Capasso, P. Li, X. Zhang and P. Anversa
Department of Medicine, New York Medical College, Valhalla 10595.
To determine the effects of chronic coronary artery narrowing on myocardial
contractile performance, nonocclusive constriction of the left coronary
artery near its origin was surgically induced in rats and global cardiac
hemodynamics, left and right myocardial mechanics, and the magnitude and
distribution of tissue damage and interstitial fibrosis in the left
ventricular wall were analyzed 1 mo later. Reductions in coronary artery
luminal diameter of 55% resulted in left ventricular failure as
characterized by decreases in systemic arterial pressures, systolic
ventricular pressure, rise and decay in first derivative of left
ventricular pressure (+/- dP/dt), and an increase in left ventricular
end-diastolic pressure. Right side dysfunction was also present as
documented by an elevation in right ventricular end-diastolic pressure and
a reduction in -dP/dt. In vitro measurements of papillary muscle mechanics
revealed a biventricular reduction in isometric developed tension and peak
rates of tension rise and decay. Moreover, the kinetic parameters of
isometric contraction duration, time to peak tension and time to one-half
relaxation, were significantly shorter in left muscles from coronary
artery-narrowed animals. Isotonically, peak muscle shortening was reduced
in the left muscle, whereas time to peak shortening was prolonged in the
right myocardium. In addition, the velocities of muscle shortening and
relengthening were decreased in both ventricles. Foci of replacement
fibrosis and diffuse interstitial fibrosis were found in the epimyocardium,
midmyocardium, and endomyocardium, demonstrating that a significant amount
of myocyte loss occurred throughout the left ventricular wall.(ABSTRACT
TRUNCATED AT 250 WORDS)
