Effects of changes in sodium balance on leucocyte sodium transport: qualitative differences in normotensive offspring of hypertensives and matched controls.

ABSTRACT

To investigate the effects of changes in sodium balance on blood pressure and leucocyte sodium transport, normotensive first-degree relatives of hypertensive patients and control subjects were randomized to receive low- and high-salt diets for 2 weeks, separated by a wash-out period of 2 weeks. High-salt intake failed to alter blood pressure, whereas the low-salt diet produced significant falls in standing pressures in both groups. In the control subjects leucocyte sodium efflux was not changed by either manoeuvre, but in the relatives low-salt diet stimulated ouabain-insensitive sodium efflux rate constant. There was a significant qualitative difference in the pattern of response of total efflux rate constant to the two dietary periods between the two groups of subjects. These data are not compatible with the release of a humoral sodium pump inhibitor in response to sodium-induced volume expansion, and lend support to a disturbance of membrane permeability to sodium in subjects genetically prone to hypertension.