Salt-sensitivity in normotensive elderly.

Up to now little has been known about mechanisms of salt sensitivity as well as causes of increasing frequency of salt-sensitivity and its distribution in elderly population. Data regarding activation of renin-angiotensin-aldosterone system in the elderly are quite controversial . Number of studies showed increased plasma rennin activity (PRA) while others indicate decreased renin levels. The study aimed to assess salt-sensitivity in normotensive young and elderly men. and assess their renin profile. Salt sensitivity was assessed in normotensive 44 young and 58 elderly males. Salt sensitivity was assessed by the difference of mean arterial pressure (MAP) on high (200 mmol/day) vs. low (40 mmol/day) sodium diet. Plasma rennin activity (PRA) was assessed during both diets. High salt diet led to significant increase in systolic blood pressure and MAP only in salt-sensitive subjects with peak levels in the elderly. Only salt-resistant subjects responded adequately during high salt diet by decrease in PRA which was significantly lower compared to basal levels. In salt-sensitive groups, especially in the elderly, PRA decreased to a lesser extent. Final clarification of mechanisms of salt-sensitivity in normotensive elderly further investigations is needed.