Natriuresis and carbohydrate-induced antinatriuresis in fasted, hydrated hypertensives.

After an overnight fast and oral hydration with water, hypertensive subjects developed a significant natriuresis (mean urine sodium excretions increased from 130 to 291 mueq/min. The incidence of a natriuresis (greater than 200 mueq sodium excreted per minute) was 75% in the hypertensive group (16 subjects) compared to 27% in a previously studied normotensive group (22 subjects). The incidence of a carbohydrate-induced antinatriuresis (greater than 30% decrease in urinary sodium excretion) was 62% in the hypertensive group compared to 41% in the normotensive group. No decrease in plasma volume (131I-labeled albumin concentration) due to a shift of solute and water intracellularly could be documented to explain the antinatriuretic effect of glucose. An incidental observation was a significant decrease in plasma zinc concentrations after glucose ingestion.