Effects of exercise training on the biosynthesis of prostacyclin and thromboxane in rats

The effects of exercise training on eicosanoid levels were studied in male Wistar rats. One‐month‐old rats were trained on a drum exerciser at an intensity of around 70% of maximal oxygen consumption for 10 weeks (60 min day^‐1, 5 days week^‐1) after familiarization. Some animals of the same age did not exercise and served as a control. Two days after training, several blood vessels, including thoracic aortae, inferior vena cavae, external iliac arteries, external iliac veins, common carotid arteries and jugular veins, were excised and incubated for 10 min. Basal release of prostacyclin from these vessels was determined using [¹²⁵I]radio‐immunoassay (RIA) of 6‐keto‐PGF_1α. The levels of plasma prostacyclin and urinary metabolites of prostacyclin and thromboxane were also determined by RIA. Our results showed that trained animals had lower body weight and urine II‐dehydro‐thromboxane B₂ levels than the controls (P < 0.001 and P< 0.05, respectively). In contrast, urinary 2,3‐dinor‐6‐keto‐PGF_1α level was elevated after training (P< 0.05). Nonetheless, prostacyclin levels in plasma and from various dissected vessel segments, except thoracic aorta, did not change significantly after training. These findings suggest that exercise training may affect endogenous eicosanoid levels by increasing the basal release of prostacyclin and reducing the basal thromboxane level.