Intralymphocytic sodium and free calcium concentration in relation to salt sensitivity in patients with essential hypertension.

Abstract

In order to clarify the relation between salt sensitivity and changes in intracellular sodium ([Na]i) and free calcium concentration ([Ca2+]i) after salt loading, [Na]i and [Ca2+]i were determined in lymphocytes of twenty patients with essential hypertension under a low salt diet (3 g/day) and a high salt diet (20 g/day) for seven days, respectively. They were classified as "salt-sensitive" (n = 10) or "nonsalt-sensitive" (n = 10) on the basis of the changes in blood pressure after salt loading. Both lymphocytic [Na]i and [Ca2+]i were significantly increased with salt loading in salt-sensitive patients (p less than 0.05 for both), while they were not affected by salt loading in nonsalt-sensitive patients. Lymphocytic [Ca2+]i showed a positive correlation with lymphocytic [Na]i under both low salt diet (r = 0.62, p less than 0.01) and high salt diet (r = 0.70, p less than 0.01) in all patients in both groups. In addition, a close and positive correlation was observed between the changes in lymphocytic [Na]i and those in lymphocytic [Ca2+]i after salt loading in all patients in both groups (r = 0.80, p less than 0.001). These results suggest that the increase in [Ca2+]i, possibly linked with the increase in [Na]i, may be involved in elevation of blood pressure in the salt-sensitive patients after salt loading.