The effects of bumetanide on renal function and blood composition in sheep.

Respones to bumetanide were studied in five ewes. During ADH infusion urine flow increased from less than 1-0 to approximately 11-5 cm3 min-1 within 30 min of intravenous injection of 0-02 mg kg-1 bumetanide and returned to approximately 2-0 cm3 min-1 within 3 h of dosing. The diuresis was accompanied by large increases in sodium and chloride excretion and smaller increases in potassium and free hydrogen ion excretion. Bicarbonate excretion and TCH20 were reduced. Plasma potassium and chloride concentrations decreased slightly while arterial bicarbonate pH and pCO2 slightly increased. A transient increase in GFR and RPF was followed by a small reduction in GFR. No change in CH20 was observed after bumetanide injection during water diuresis. Increasing the dose of bumetanide over the range 0-002 to 0-20 mg kg-1 resulted in more pronounced and prolonged responses. The results show that bumetanide is a potent diuretic in sheep with its main site of action on the ascending limb of Henle's loop.