Total intracellular calcium content and sodium transport in erythrocytes of essential hypertensive patients.

To estimate the amount of Ca bound to the inner aspect of the membrane of human erythrocytes, a method was developed to determine the total intracellular calcium content (Cai) using flameless atomic absorption. The mean Cai was 1.65 +/- 0.34 mumol/l cells in normotensive individuals (range 1.1-2.4). In untreated essential hypertensive patients Cai was slightly reduced, the difference being not significant. Antihypertensive treatment possibly affects Cai. Plasma ionized Ca and total plasma Ca tended to be lower and higher in the hypertensive patients, respectively. The activities of red cell Na-K co-transport, Na-Li exchange and the Na-K pump were inversely correlated to Cai in normotensives (P less than 0.05). The relations of Cai to Na-K co-transport and Na-Li exchange were displaced to higher values in untreated essential hypertensive patients.