Plasma renin activity in sheep pregnancy after fetal or maternal nephrectomy.

The effect of bilateral fetal or maternal nephrectomy on basal and diuretic-stimulated plasma renin activity (Pra) was examined in 9 chronically catheterized Dorset sheep. After fetal nephrectomy, there was an initial rapid decrease in fetal PRA with t1/2 of 42-84 min, followed by a slower decrement with 1/2 350-720 min. There was no change in maternal PRA during this period. Similarly, after maternal nephrectomy, the decrease in maternal PRA had two exponential components and there was no associated change in fetal PRA. These data, and the maternal and fetal PRA responses to intravenous furosemide, have demonstrated that renin does not cross the sheep placenta and that fetal PRA is independent of the maternal PRA level.