Effect of hydrochlorothiazide on renal electrolyte gradient in glucose diuresis and experimental diabetes insipidus.

Hydrochlorothiazide (100 mg/kg, i.v.) did not affect the renal electrolyte gradient in uninfused dogs. The renal electrolyte gradient was obliterated by infusion of 5% glucose alone (10 ml/min). Renal medullary sodium fell from 225 to 68 mEq/liter. The gradient was not re-established upon concurrent administration of hydrochlorothiazide. An essentially normal renal sodium gradient was present in rats with experimental diabetes insipidus. Polyuria and polydipsia were suppressed by chlorothiazide or hydrochlorothiazide with no change in the renal sodium content.