Journal of Applied Physiology, Vol 62, Issue 1 328-334, Copyright © 1987 by American Physiological Society
Effect of hypertension on hearts of rats trained by swimming
T. Schaible, A. Malhotra, G. Ciambrone, P. Buttrick and J. Scheuer
To determine whether a prior chronic swimming program would alter the
heart's response to chronic hypertension, female rats were made to swim for
10 wk, and then the left renal artery was stenosed. Heart perfusions were
performed 10 wk later. The five groups studied were: control (C),
normotensive swimmers (Sw), sedentary hypertensives (H), swimming rats made
hypertensive and then allowed to be sedentary (Sw-H-Sd); and swimming
animals made hypertensive and continued in a swimming program (Sw-H-Sw).
Total heart and left ventricular weights were increased in increasing
degrees in the sequence Sw, H, Sw-H-Sd, and Sw-H-Sw. Right ventricular
weight was only increased in Sw and Sw-H-Sw. Swimming before the onset of
hypertension enhanced total cardiac output and stroke work. Ejection
fractions and mean velocity of circumferential fiber shortening (Vcf) were
increased in Sw-H-Sd or Sw-H-Sw vs. controls. Myocardial O2 extraction was
increased and coronary flow and myocardial O2 consumption were diminished
in all hypertensive groups. However, lactate production was similar in all
groups. Myosin adenosinetriphosphatase activity was increased in Sw but
decreased in the three H groups. The percent of V1 myosin isozyme was
greater and the percent of V3 less in Sw than in C; V1 was diminished and
V3 increased in H and Sw-H-Sd; isozymes were normal in Sw-H-Sw.(ABSTRACT
TRUNCATED AT 250 WORDS)
