THE TRANSFER OF WATER AND SODIUM TO THE AMNIOTIC FLUID OF THE GUINEA PIG

Abstract

The transfer of water and of Na to the amniotic fluid of the guinea pig was studied from the end of the 1st 3d of pregnancy to term, using heavy water (DHO) and radioactive Na (Na24) as the tracer materials. A vol. of water approx. equal to the total vol. of the amniotic fluid flows into and out of the amniotic sac about once an hr. in the earlier stages of pregnancy and about once every 40 mins. in the later stages. Only about 1/50 of the Na of the amniotic fluid is replaced in the same time interval. This means that water moves into and out of the amniotic fluid on the avg. 50 times more rapidly than Na. The rate of replacement of the water of the amniotic fluid is astonishingly rapid and is at variance with the concept that the amniotic fluid is relatively stagnant.