Comparison of bumetanide and hydrochlorothiazide on renal potassium and hydrogen ion excretion

The purpose of this study was to compare the renal electrolyte excretion pattern of bumetanide with that of hydrochlorothiazide in dogs anesthetized with pentobarbital. In bumetanide-treated animals, mean sodium excretion rose to 12 per cent of the filtered load, while hydrochlorothiazide increased sodium excretion to 4 per cent of the filtered load. After bumetanide, urine pH fell from 6.1 to 5.1 and net hydrogenion excretion increased significantly. After hydrochlorothiazide, urinary pH went from 6.4 to 7.4, and there was no change in net hydrogen ion excretion. Potassium excretion rose to 106+/-22 muEq/min with bumetanide and to 99+/-17 muEq/min with hydrochlorothiazide. These changes in electrolyte excretion occurred despite lack of changes in arterial blood gases, arterial blood pressure, and glomerular filtration rate. In addition, bumetanide did not exert an inhibitory effect on potassium excretion under conditions of potassium loading. It is concluded that bumetanide produces a higher urinary Na+:K+ ratio with a lower pH than hydrochlorothiazide and that renal potassium ion excretion in response to sulfamoyl diuretics is not solely dependent on the rate of sodium excretion.