Estimation of urinary kininogenase activity using bovine serum low molecular weight kininogen

Estimation of urinary kininogenase activity by radioimmunoassay of generated kinin was studied. Bovine serum low molecular weight kininogen was proved not to cross-react with kallidin antibody and also bradykinin antibody. This kininogen was used as substrate measuring urinary kininogenase activity. Separation of released kinin from the kininogen was not required in the present method. Urinary kallikrein activity was found to be significantly decreased in essential hypertension, in chronic glomerulonephritis and in patients who had received renal transplantation. On the contrary, an increase in urinary kallikrein was found in primary aldosteronism and in Bartter's syndrome. The present method was very useful for measuring kininogenase activity.