Renal sodium handling abnormalities in hypertensive and normotensive patients with a family history of hypertension

We measured the effective renal plasma flow, the glomerular filtration rate and the fractional excretion of sodium under low and high sodium intakes in the normotensive offspring of hypertensives and in essential hypertensive patients. During the high sodium intake, 57% of the offspring and 42% of the hypertensive patients showed an increase in effective renal plasma flow and fractional excretion of sodium. In the remaining hypertensives, enalapril improved the renal haemodynamic and sodium-handling responses. Enalapril also reduced the blood pressure in all hypertensives, whether they showed a normal or an abnormal response to a high sodium intake. In the hypertensive patients with an abnormal response to a high sodium intake, the intra-erythrocyte sodium content was higher than in the normal responders. Thus, abnormal renal haemodynamic and sodium-handling responses to a high sodium intake were observed in 50% of the hypertensive patients and the offspring. The high intra-erythrocyte sodium content observed in the hypertensive patients suggests that extrarenal alterations in sodium handling were present.