Amiloride, frusemide and urinary kallikrein excretion

Intravenous administration of the loop diuretic frusemide caused a rapid but short-lived increase in the urinary excretion of kallikrein-like activity in healthy volunteers. Indomethacin alone did not alter urinary electrolyte or kallikrein excretion, but when given concurrently with frusemide it blunted the natriuresis without altering the urinary kallikrein excretion. A single oral dose of amiloride, a distal tubular diuretic, caused a natriuresis but no significant change in urinary kallikrein excretion. The results do not support a direct role for the renal kallikrein-kinin system in mediating the natriuresis induced by diuretics.