Abstract

The stop-flow procedure was used to assess and localize actions of chlorothiazide, trichlormethiazide, and hydrochlorothiazide on reabsorption, of electrolytes in the distal portion of the renal tubule.

All three agents interfered with the mechanisms by which the distal tubule reduces sodium, chloride, and potassium concentration of urine to low levels during occlusion. The mercurials, chlormerodrin and meralluride, did not alter distal minima of these three electrolytes.

Chloride distal minimum was more greatly increased than was the sodium minimum, indicating that this anion was probably retained in distal urine in order to balance increased potassium levels derived from enhanced secretion and, possibly, from reduced reabsorption.

Data included in this report do not support or rule out proximal actions of benzothiadiazines.