Potassium transport in kidney and placenta in normal pregnancy and in experimental toxemia

Abstract

Under aerobic conditions the steady state of potassium exchange has been measured with K42 in slices of rat kidney cortex and placenta. In the steady state the total time of incubation was 80 minutes during which the O2 uptake was determined. At different time intervals samples of the medium and tissues were taken for measurement of K by flame-photometry and radioactivity. Tissues from nonpregnant and pregnant rats (14 to 20 days gestation) fed a normal pellet diet were controls. The results were compared with data obtained from pregnant and nonpregnant rats fed a vitamin E deficient diet containing toxic fractions of oxidized cod liver oil. Under all experimental conditions kidney cortical tissue showed similar exchange rates. A steady increase of exchange until the end of gestation was observed in placental tissue of normal pregnant rats. In comparison, in rats fed the special diet there was a higher rate of K exchange on the fourteenth to sixteenth days of gestation which then dropped below normal pregnant values towards the end of gestation. The QO2 indicated partial respiration dependency of the K transport variations. This suggests an increasing demand for K in fetal metabolism in normal pregnancy and an interference with the rate of exchange of K in placental tissue by this dietary means.