Exogenous factors influencing the human erythrocyte sodium–lithium countertransport system

Abstract
It has recently been found that the Na+–Li+ countertransport across the human erythrocyte membrane is increased in patients with essential hypertension. We investigated the influence of hypokalaemia, oral contraceptives, diabetes mellitus and essential hypertension on the activity of this transport system.Normal values for the maximal Na+–Li+ transport rate were 0·25pL0·08 mmol l‐1 h‐1 (males, n= 18) and 0·23pL0·06 (females, n= 14). We found elevated values in women taking oral contraceptives (0·34pL0·07, n= 10, Pn= 13, Pn= 24, P+–Li+ countertransport by hormones. Thus the transport rate does not seem to be an appropriate test for the diagnosis of essential hypertension.