Effect of Prostaglandin l 2 on Ovine Maternal and Fetal Adrenal Blood Flows 1

Abstract

Summary

Fetal (n = 6) and maternal (n = 7) adrenal blood flows were measured with radioactive microspheres in chronically catheterized sheep, before and 90 sec after the injection of prostaglandin I₂. Adrenal vascular resistance is defined as the mean arterial pressure (maternal) or arteriovenous pressure difference (fetal) divided by the adrenal blood flow. Both the mother and the fetus responded with a decrease in blood pressure from 103 ± 5.4 to 64 ± 5.7 mm Hg and 39.0 ± 1.2 to 28.0 ± 1.8 mm Hg, respectively. Adrenal vascular resistance per gram also decreased in the mother from 72.00 ± 6.65 to 52.60 ± 6.62 mm Hg/(ml/min)/g and in the fetus from 11.8 ± 1.0 to 6.1 ± 1.6 mm Hg/(ml/min)/g. Prostaglandin I₂ did not significantly change the flow per gram to the maternal adrenals. The fetal adrenal flow per gram doubled in response to prostaglandin I₂. As the doses of prostaglandin I₂ are dissimilar the magnitude of the changes cannot be compared. However, prostaglandin I₂ caused vasodilatation in both the maternal and fetal adrenals. Fetal adrenal control blood flows were significantly (P < 0.001) greater than the maternal control adrenal blood flows.