Uterine vascular response to prostacyclin in nonpregnant sheep

Two effects of prostacyclin (PGI2) on uterine blood flow were investigated in nonpregnant, castrated ewes with chronically implanted polyvinyl catheters and electromagnetic flow probes. Intra-arterial infusion of PGI2 resulted immediately in increased uterine blood flow, which returned rapidly to baseline after termination of the infusion. A dose-response curve was constructed and demonstrated that a uterine arterial PGI2 concentration of 1.2 times 10(-6)M (0.5 microgram/ml) produced flows 50% of those achieved by a reference dose of 1 microgram of 17 beta-estradiol. Increases in uterine blood flow were not associated with changes in mean systemic arterial pressure. These findings demonstrate that PGI2 has a vasodilatory effect on the uterine circulation and suggest that this substance has a role in the regulation of uterine blood flow.