GLUCOSE-LOAD AND RENAL SODIUM HANDLING IN MILD ESSENTIAL-HYPERTENSIONON DIFFERENT SODIUM INTAKES

The aims of the present study were to investigate the effects of chang es in sodium intake in patients with untreated mild essential hyperten sion on the hormonal (plasma renin activity and aldosterone) and renal tubular responses to short-term hyperinsulinemia as achieved by an or al glucose tolerance test (OGTT), Fourteen patients with essential hyp ertension (mean age, 46 years; average blood pressure (BP), 151/96 mm Hg) were studied, After a 1 week run-in period on their usual diet the y entered a randomized double-blind crossover study of a week of low ( 10 mmol/day) vs a week of high (350 mmol/day) sodium intake, On the la st day of each diet they underwent a standard 2-h OGTT, Blood and urin es were taken hourly and segmental tubular sodium handling was assesse d by the endogenous lithium clearance. The results demonstrate that th e plasma insulin and glucose response to a short-term oral glucose loa d were not influenced significantly by the changes in dietary sodium i ntake, However, the glucose load was associated with marked renal sodi um retention in the absence of any change in systemic BP, The reductio n in renal sodium excretion was independent of circulating aldosterone taut appeared to be due to an increase in renal distal tubular re-abs orption.