The Effect of Sar¹Ala⁸ AII on Ovine Uterine and Umbilical Blood Flow

Abstract

The effects of Sar¹Ala⁸ AII (Saralasin), an angiotens in II (AII) receptor blocker, were examined in the late gestation ewe and fetus. Maternal administration of Saralasin resulted in a reduction in both mean maternal systemic arterial pressure and uterine blood flow. There were no changes in the measured fetal indices during maternal drug administration. Infusion of Saralasin to the fetus caused variable reductions in mean fetal arterial blood pressure and umbilical flow. There were no changes in maternal parameters measured. Therefore, in pregnant sheep in the third trimester, a component of normal uterine blood flow is maintained by endogenous AII, primarily through maintenance of adequate perfusion pressure. On a short term basis, there i s no response i n the fetus to maternal A11 receptor blockade. There i s no apparent inter-relationship between endogenous fetal AII receptor activity and uterine blood flow. Fetal perfusion pressure t o the umbilical circulation is maintained by endogenous AII only i n some animals.