Differential Effects of Prostaglandins A 1 and A 2 on Pulmonary Vascular Resistance in the Dog 1

Abstract

Summary

The effects of PGA₁ and PGA₂ were studied in the canine pulmonary vascular bed. Infusion of PGA₁ into the lobar artery decreased lobar arterial and venous pressure but did not change left atrial pressure. In contrast, PGA₂ infusion increased lobar arterial and venous pressure and the effects of this substance were similar in experiments in which the lung was perfused with dextran or with blood. These data indicate that under conditions of controlled blood flow PGA₁ decreases pulmonary vascular resistance by dilating intrapulmonary veins and to a lesser extent vessels upstream to the small veins, presumably small arteries. The present data show that PGA₂ increases pulmonary vascular resistance by constricting intrapulmonary veins and upstream vessels. The predominant effect of PGA₂ was on upstream vessels and the pressor effect was not due to interaction with formed elements in blood or platelet aggregation.