Specific hemodynamic effects of PGE 2 and PGF 1α in the canine lung

Abstract

The differential effects of two pulmonary vasoconstrictors, prostaglandin E 2 (PGE 2) and F 1α (PGF 1α) on capillary pressure and the distribution oft vascular resistance were studied in isolated, blood perfused canine lung lobes. Each lobe was inflated to a constant airway pressure (3 cmH 2O) and perfused in Zone III conditions at constant flow (431 ± 36 ml/min). Pulmonary arterial and venous pressures were measured at the inflow and outflow orifices, respectively. Pulmonary capillary pressure (P c) was determined via a double occlusion technique and pre- and postcapillary resistances calculated. PGE 2, and PGF 1α, administered as rapid intra-arterial boluses (10–300 μg), increased arterial pressure in a dose-dependent fashion. However, at each dose, the increase in vascular resistance was more pronounced in postcapillary segments. The increase in postcapillary resistance was 5 and 3.5 times greater than the increase in precapillary resistance at the highest dose of PGE 2 and PGF 1α used in this study, respectively (300 μg). As a result, P c measured at the peak of the vascular response increased by 2 to 19 cmH 2O over control values with PGE 2 and by 5 to 13 cmH 2O over control values with PGF 1α the prostaglandin dose was varied from 10 to 300 μg. We conclude-that the predominant effect of these prostanoids is to increase postcapillary resistance and pulmonary capillary pressure.