PLACENTAL-TRANSFER OF ALDOSTERONE IN THE GUINEA-PIG DURING LATE PREGNANCY

The rates of foeto-maternal exchange and metabolism of aldosterone were calculated from experiments in which the labeled hormone was infused at a constant rate into the maternal and foetal circulations of the guinea-pig during the last few days of intrauterine life. It was found that d-[1,2,6,7-3H]-aldosterone crossed the placenta from the mother to the foetus and in the reverse direction. The maternal to foetal, as well as the foetal to maternal ratios of the tracer, increased between 60 and 67 days of gestation. The maternal contribution to the concentration of aldosterone in the plasma of the foetus was of 23.8 % at 64 days and 35.7% at 67 days. At least 60% of the aldosterone in the foetal plasma was of foetal origin. The foetus contributed very little to the concentration of aldosterone in the plasma of the mother. © 1979.