Regulation of Aldosterone Production During Pregnancy in the Rat1

Plasma renin activity (PRA) and in vitro aldosterone production were determined in two strains of rats given normal and low sodium diets during pregnancy. The effects of sodium deprivation on the fetal renin—aldosterone system was also examined. In one strain of rats, PRA was not increased during pregnancy, but was increased during sodium depletion. Aldosterone production increased during pregnancy, but changed no further during sodium depletion. In the second strain of rats, both PRA and aldosterone production increased during pregnancy and were not further stimulated by sodium depletion. Fetal aldosterone production was increased by maternal sodium depletion in both strains, whereas, renal renin content remained unchanged. Plasma K in the mother was increased in pregnancy and increased further with sodium depletion. These data suggest that increased plasma K may be the stimulant for increased aldosterone production observed during pregnancy in the rat, and may also be a controlling factor in fetal aldosterone production. (Endocrinology92: 1208, 1973)