AJP - Heart and Circulatory Physiology, Vol 256, Issue 1 66-H73, Copyright © 1989 by American Physiological Society
Alterations of coronary blood flow and reserve with aging in Fischer 344 rats
R. Hachamovitch, P. Wicker, J. M. Capasso and P. Anversa
Department of Pathology, New York Medical College, Valhalla 10595.
To determine whether aging affects the coronary circulation, left and right
ventricular coronary blood flow and vascular resistance at rest and after
maximal vasodilation were measured by left atrial injection of radioactive
microspheres in conscious, unrestrained male Fischer 344 rats at 4, 12, and
20 mo of age. As a function of age, maximal coronary blood flow per 100 g
of tissue decreased by 43% in the left ventricle at both 12 and 20 mo,
whereas a 44 and a 47% reduction was found in the right side of the heart
at the same time intervals. Minimal coronary vascular resistance per 100 g
of myocardium increased by 56 and 36% in the left ventricle and by 48 and
44% in the right at 12 and 20 mo, respectively. No change was found in
total minimal coronary resistance for either ventricle despite an increase
in myocardial mass. Maximal coronary blood flow per 100 g to the
endocardium was depressed more than epicardial flow, leading to a 24%
reduction in the endocardial-to-epicardial flow ratio at 20 mo. Coronary
vascular reserve per 100 g, expressed as the increase in coronary blood
flow during maximal coronary vasodilation, was greater in the right than in
the left ventricle at all ages. It is concluded that the changes in
coronary hemodynamics associated with maturation and aging are comparable
with those seen in pressure overload hypertrophy with an increased
vulnerability potential of the myocardium to ischemic episodes,
particularly of the subendocardial region of the left ventricle.
