The effect of diuretics on components of the urinary kallikrein-kininogen-kinin system in man.

The effects of acute infusions of diuretics on components of the human urinary kallikrein-kininogen-kinin system were determined. Normal human subjects were given infusions of chlorothiazide and furosemide in doses calculated to produce a comparable natriuresis and diuresis. Alterations in urine electrolyte excretion, kinins, total and intact kininogen, and total active kallikrein were determined before and after the diuretic administration. Chlorothiazide caused a significant increase in total, but not active, kallikrein and had no effect on kinins and total or intact kininogen. Furosemide did not alter total or active kallikrein, or intact kininogen, but did decrease kinin and total kininogen excretion significantly. These differences in effects were not related to urinary sodium excretion or urinary flow because both diuretics produced comparable effects on these parameters. We conclude that acute infusions of diuretics do not activate the kallikrein-kininogen-kinin system and that some of the previously described effects of diuretics on this system may be related to their site of action.