Intrinsic myocardial function and oxidative stress after exhaustive
exercise.
Seward, Stephen W., K. Stephen Seiler, and Joseph W. Starnes.
Department of Kinesiology, University of Texas at Austin, Austin,
TX 78712
APStracts 2:0129A, 1995.
The purpose of this study was to determine the effect of an exhaustive
running bout on intrinsic myocardial function using the isolated
working rat heart, and to determine if exhaustive exercise resulted
in measurable oxidative stress in the myocardium. Untrained,
familiarized male rats were run at 18 m/min 0% grade until exhausted.
Run time to exhaustion was approximately 75 minutes. Post-exhaustion
isolated heart measurements of cardiac output, rate pressure product
(RPP) at low and high workloads, maximum left ventricular pressure,
or 50 minutes performance at 85% of peak RPP were not different from
those of non-exercised, perfused control hearts. Exhaustive exercise
resulted in a significant decline (174 vs. 224 nmols/g ww, P<0.05) in
non-protein non-glutathione sulfhydryls, a thiol fraction indicative
of oxidative stress. However, the magnitude of this measure of
oxidative stress appears insufficient to cause alterations in
intrinsic myocardial performance. We conclude that healthy, untrained
rats subjected to exhaustive exercise fail to demonstrate
accumulation of a functionally significant level of myocardial
oxidative stress.
Received 10 August 1994; accepted in final form 14 March 1995.
APS Manuscript Number A837-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 4 April 1995.