Cell membrane handling of sodium in lymphocytes during salt restriction in normotensives

Lymphocyte sodium content and sodium efflux were studied in 9 healthy normotensive males without history of essential hypertension before, during and after 5 weeks of severe sodium depletion. Sodium depletion caused a significant increase in sodium content and a slight but non-significant decrease in potassium content. Total and ouabain-sensitive sodium efflux rate constants decreased significantly during sodium depletion, while absolute sodium efflux, derived from cellular sodium concentration and the corresponding sodium efflux rate constants, remained unchanged. A significant reduction in arterial mean and diastolic blood pressure, measured by ambulatory as well as by home readings, was observed during salt restriction. Prolonged severe sodium depletion of normotensive subjects leads to changes in lymphocytic sodium homeostasis, probably due to a primary inhibition of the sodium pump and a secondary intralymphocytic sodium accumulation. The mechanism underlying these changes remains unclarified.