Baroreceptor and prostanoid control of fetal renal cortical blood flow andplasma renin activity

Renal function in the fetus is important for maintenance of fetal fluid and electrolyte balance. This study was performed to test the role of prostagl andins and their interaction with arterial baroreceptors and chemoreceptors in the control of renal cortical blood flow during hypotension produced by vena caval obstruction in late-gestation fetal sheep. We studied 18 time-d ata chronically catheterized, fetal sheep (124-136 days gestation). Fetuses were either studied intact (n = 11) or sinoaortic denervated (n = 7), and each fetus was studied twice, with and without pretreatment with indomethac in (0.2 mg kg(-1), i.v.). Each fetus was subjected to hypotension caused by vena caval obstruction for 10 min. Before hypotension, renal cortical bloo d flow was higher in the vehicle-treated sinoaortic denervated fetuses than in vehicle-treated intact fetuses. The increased renal cortical blood flow observed in the sinoaortic denervated fetuses was counteracted by indometh acin, so that the difference between sinoaortic denervated and intact fetus es was eliminated after indomethacin treatment. Hypotension decreased renal blood flow equally in all groups. Plasma renin activity was increased in r esponse to hypotension in the intact fetuses, but not in the sinoaortic den ervated fetuses. Indomethacin treatment, by itself, did not alter plasma re nin activity. It is concluded that both arterial baroreceptors and prostano ids influence renal blood flow. Further. renin secretion is influenced by a rterial baroreceptors and chemoreceptors and there is no apparent modulator y effect of prostanoids on the baroreflex control of renin secretion.