SUBSTANTIAL REDUCTIONS IN BLOOD-PRESSURE AFTER BILATERAL-NEPHRECTOMY IN FETAL SHEEP

The role of the kidneys in the maintenance of arterial blood pressure was examined in fetal sheep. Surgery was performed on 11 pregnant shee p (8 twin pregnancies) at similar to 125 days. All 19 fetuses were ins trumented with hindlimb arterial and venous catheters. Eleven of the f etuses (but only 1 of each twin) were also bilaterally nephrectomized. Fetal arterial blood pressure was measured several times between 2 an d 14 days after surgery. Arterial blood pressure in the intact fetuses increased from 44+/-1 to 47+/-1 mmHg (SE) but gradually decreased fro m 37+/-4 to 25+/-3 mmHg in the nephrectomized group. Whereas the arter ial blood pressures measured on the first day of the experiment were n ot statistically significantly different between the two groups, by th e final day of the experiment the arterial blood pressure of the intac t fetuses was much higher than that of the nephrectomized fetuses. Ven ous blood pressure was similar in the two groups. We conclude that bil ateral nephrectomy in fetal sheep not only stops the normal gestationa l increase in arterial blood pressure but also leads to a progressive decline.