Effects of changes in dietary sodium intake on normotensive subjects with and without a genetic predisposition to essential hypertension.

Twenty-two young normotensive male subjects, 12 with an established family history of essential hypertension, were put on a low-followed by a high-sodium diet. Plasma from each dietary period was tested for inhibitory activity on Na-K-ATPase using three different techniques: measurement of 22Na efflux rate, measurement of 3H ouabain binding characteristics and a bioluminescent adenosine triphosphate assay. The high-sodium diet was associated with a diminished ouabain-sensitive sodium efflux rate constant in the whole group; however, no circulating inhibitor could be detected in the plasma. Those with and those without a family history of essential hypertension were indistinguishable. The results suggest that young normotensive individuals with a genetic predisposition to essential hypertension do not produce a circulating inhibitor of sodium-potassium adenosine triphosphatase (Na-K-ATPase) in response to a high-sodium challenge.