Effect of bisenoic prostaglandins on the uterine vasculature of the nonpregnant sheep.

The effects of the bisenoic prostaglandins on the uterine vasculature and uterine contractile activity have been evaluated in an unanesthetized chronically catheterized nonpregnant sheep preparation. Changes in uterine blood flow were monitored with electromagnetic flow probes while uterine contractile activity and tone were determined via an intra-uterine balloon connected to a pressure transducer. Prostaglandins A2, D2, E2, and prostacyclin (PGI2) were all found to be vasodilators. PGD2 and PGI2 were much more potent than PGA2 and PGE2 in dilating the uterine vasculature. The prostacyclin breakdown product 6-keto PGF1 alpha, PGF2 alpha, thromboxane B2, and the endoperoxide analogues U44069 and U46619 produced vasoconstriction of the uterine vasculature. Prostaglandins A2, D2 and F2 alpha increased while PGI2 decreased uterine contractile activity. PGF2 alpha also increased uterine tone suggesting that a portion of its vasoconstrictor activity may be due to mechanical compression of the uterine vasculature.