Piretanide and urinary excretion of ions in rat. Effect of indomethacin.

1. Piretanide is a new loop diuretic resembling furosemide. The effects of this diuretic on various parameters of renal function and on the excretion of the major ions were studied on anaesthetized, hydrated rats. 2. Piretanide induced a marked diuresis and increased sodium, potassium, chloride and calcium excretion. Calcium excretion increased more than that of sodium. Urinary osmolality and water reabsorption decreased. 3. Inulin clearance and phosphate excretion were significantly altered by piretanide. 4. Pretreatment of rats with indomethacin did not suppress the effects of piretanide on diuresis nor its effects on urinary excretion of sodium, chloride and potassium, since these parameters increased in the same proportion in the presence or in the absence of indomethacin. 5. Pretreatment with indomethacin abolished piretanide-induced dissociation of sodium and calcium excretions.