Effect of nicardipine on renal sodium handling in normotensive insulin-dependent diabetics and controls.

In 12 newly diagnosed normotensive insulin-dependent diabetics and eight controls, we compared the effects of acute nicardipine administration on renal haemodynamics and segmental tubular movement of sodium assessed as by lithium clearances. Both in the controls and the insulin-dependent diabetics, nicardipine induced similar haemodynamic changes, including a mild decrease in mean arterial pressure and renal vascular resistance, whereas the glomerular filtration, renal plasma flow and filtration fraction were unchanged. Despite a fall in blood pressure, nicardipine exerted a marked natriuretic effect in both groups, which appears to have been primarily due to a decrease in distal reabsorption and, to a lesser extent, in proximal reabsorption.