Placental Hormones and Elevation of Erythrocyte Sodium-Lithium Countertransport in Pregnancy

Abstract

Red cell Na-Li countertransport was measured in 42 normotensive women after the 25th week of pregnancy, 38 normotensive controls and 31 patients with essential hypertension. Normotensive pregnant subjects have elevated values of Na-Li countertransport compared to normotensive controls (p < 0.001). This elevation was similar to the one found in hypertensive non-pregnant patients. In pregnancy, Na-Li countertransport was positively correlated with serum triglycerides (p < 0.05) and basal plasma renin activity (p < 0.05). A positive correlation was found with plasma levels of Bl-specific protein of pregnancy (p <0.05), with human placental lactogen (p <0.05), but not with estriol. These findings suggest that these two placental hormones may affect the maximal rate of the Na-Li countertransport.