Marathon run stimulates more prostacyclin than thromboxane synthesis and differently in men and women.

To study the effect of strenuous physical exercise on the balance between vasodilatory and antiaggregatory prostacyclin (PGI2) and its endogenous antagonist thromboxane A2 (TxA2), we measured the urinary output of two metabolites of PGI2 (6-keto-prostaglandin F1 alfa, 6-keto, and 2,3-dinor-6-keto), as well as two metabolites of TxA2 (thromboxane B2, TxB2, and 2,3-dinor-TxB2) ten days before, during and one, three and five days after a marathon run by 15 women and ten men. The basal urinary outputs of women and men were similar. In women, 6-keto excretion increased 10-fold (p < 0.001) and in men 30-fold (p < 0.05) during the run, and 2,3-dinor-6-keto increased 2-fold in women (p < 0.05) and 7-fold in men (p < 0.05). During the run, TxB2 output increased only in women (3-fold, p < 0.05) and 2,3-dinor-TxB2 only in men (4-fold, p < 0.05). The marathon-induced changes lasted maximally one day. The greater PGI2-than TxA2-stimulation during marathon run may be involved with the favorable effects on the cardiovascular system of physical exercise.