Renal actions of azosemide. 1. Clearance investigations in dogs

The action of 5-(4-chloro-5-sulphamyl-2-thenyl-aminophenyl)-tetrazole (azosemide) on the renal function was investigated in anaesthetised dogs. Azosemide leads to a marked increase in urine flow and urinary excretion of sodium, potassium and chloride immediately after i.v. injection. The potency of azosemide is, in terms of the inhibition of fractional tubular reabsorption of electrolytes, similar to that of furosemide. The mode of action of azosemide is also comparable with that of furosemide. After azosemide, the urine contained more chloride than sodium, the fractional tubular chloride reabsorption was inhibited to a greater degree than that of sodium, the urinary pH fell and the potassium excretion increased. The glomerular filtration rate and the PAH clearance fell after high doses of azosemide, whilst the renal blood flow measured electromagnetically with a flow probe placed around the renal artery, increased even at high doses. The injection of a small dose of azosemide (0.003 mg/kg) into a renal artery led to a diuretic and natriuretic effect only in the injected kidney.