Effects of acute exercise on the biosynthesis of eicosanoids in rats.

We conducted this study to evaluate the effects of different intensities of acute exercise on the regulation of endogenous eicosanoid levels in male Wistar rats. The animals were divided into 4 groups; i.e.: control, mild exercise, moderate exercise and severe exercise. Immediately after exercise, animals were sacrificed. Plasma prostacyclin (PGI2) level and PGI2 release from two vessel segments (i.e., thoracic aorta and inferior vena cava) were determined by a specific 6-keto-PGF1 alpha (125I) radioimmunoassay. Urine thromboxane was determined by a specific 11-dehydro-TXB2 (125I) radioimmunoassay and normalized by urine creatinine. Although both plasma PGI2 and urine thromboxane tended to be elevated by severe exercise, only the increase in thromboxane was statistically significant (p <0.05). In addition, PGI2 release from both vessels were not affected by different intensities of acute exercise. We also observed that aortic PGI2 release was greater than their corresponding veins in each group. We therefore conclude that only severe acute exercise, rather than mild or moderate exercise, may affect prostacyclin-thromboxane balance in rats.