Sodium and potassium in erythrocytes of adult and fetal goats

Abstract

Sodium and potassium concentrations in the erythrocytes of adult and fetal goats were estimated by flame photometry. In the fetus there is a higher potassium and a lower sodium concentration than in the adult. The mean fetal potassium concentration is 104.8 mEq/l. of red cells and the sodium 15.8; the maternal values are 68.4 and 35.4, respectively. Pregnancy does not appear to alter the sodium and potassium concentrations in adult goat erythrocytes. Moreover, the fetal levels show no change with advancing gestation, from the 52nd to the 142nd day. The sodium and potassium gradients between the red blood cells and the plasma in fetal blood are higher than in maternal blood and suggest the possibility of an increased energy expenditure by fetal erythrocytes. The findings lend support to the hypothesis that the ionic environment within the red cell is one of the factors contributing to the differences between the oxygen dissociation curves of fetal and maternal whole blood.