THE ROLE OF PROSTAGLANDINS IN THE CORONARY BLOOD FLOW RESPONSE TO HYPOXIA IN EXERCISE TRAINED RATS
Abstract
Exercise training has been shown to potentiate the coronary flow response to stress in experimental animals. The mechanisms mediating this response are, however, poorly understood. The purpose of this investigation was to determine if prostaglandin-like activity might be involved in the training-induced changes in coronary blood flow responses to hypoxia. To test this hypothesis male Sprague-Dawley rats (N = 24) were randomly assigned to trained and untrained groups. The trained animals underwent a 16-week program that ultimately involved treadmill running up a 10% grade at 26.8 m/min for 1hr/day, 5 days/week. The untrained or sedentary group was allowed normal cage activity. Following the training, the rats were sacrificed, and their hearts were rapidly excised and placed on a modified Langendorf perfusion system under normoxic and hypoxic conditions. Coronary effluent was collected to measure coronary blood flow. Indomethacin, an inhibitor of prostaglandin production, was administered to eight rats to determine its effects on training-induced changes in coronary blood flow responses to hypoxic stress. The results of the study indicate that the trained rats had a significantly (P < .05) greater mean ((+OR-) SEM) increase in coronary blood flow during hypoxia relative to normoxia than did untrained rats (13.52 (+OR-) 2.15 vs. 9.56 (+OR-) 1.04 mL/g dry heart weight x min.('-1)). Indomethacin treatment abolished this difference and lowered coronary blood flow. Based on these results it is concluded that indomethacin antagonizes the training-induced potentiation of the coronary blood flow response to hypoxia. This suggests that the production of prostacyclin or a related compound is important to this adaptation to exercise.
Degree
Ph.D.
Subject Area
Anatomy & physiology|Animals
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