Why the study?
Does exhaustive exercise alter intrinsic myocardial function or cause functionally significant oxidative stress in untrained male rats?
Does exhaustive exercise alter intrinsic myocardial function or cause functionally significant oxidative stress in untrained male rats?
Exhaustive exercise in untrained rats causes mild oxidative stress but does not impair intrinsic myocardial function.
Exhaustive exercise induces mild oxidative stress without impairing rat myocardial function; leaves open translation to human cardiac responses.
The purposes of this study were to determine the effect of an exhaustive running bout on intrinsic myocardial function by using the isolated working rat heart and to determine whether exhaustive exercise resulted in measurable oxidative stress in the myocardium. Untrained familiarized male rats were run at 18 m/min on a 0% grade until exhausted. Run time to exhaustion was approximately 75 min. Postexhaustion isolated heart measurements of cardiac output, rate-pressure product at low and high workloads, maximum left ventricular pressure, or 50-min performance at 85% of peak rate-pressure product were not different from those of nonexercised perfused control hearts. Exhaustive exercise resulted in a significant decline (174 vs. 224 nmol/g wet wt; P < 0.05) in nonprotein nonglutathione 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.
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Seward et al. (1995) studied this question.
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