Studies on the excretion of tissue kallikrein from blood into the urine.

Enzymatically active or diisopropyl fluorophosphate-inactivated pig pancreatic kallikrein were infused intravenously into dogs. Pig pancreatic kallikrein in plasma and urine was measured by a radioimmunoassay. The total excreted pig pancreatic kallikrein was 0.8-3.1% of the administered dose when active kallikrein was infused and 21.6% when inactive kallikrein was infused. The renal clearance of the administered kallikrein was found to be between 0.9 and 4.1 ml/min, which corresponds to 2.4-6.4% of the inulin or creatinine clearance. These results indicate that renal synthesis of tissue kallikrein and its direct secretion into the urine is not the exclusive mechanism of the excretion of tissue kallikrein into the urine. A second mechanism, the renal transfer of endogenous tissue kallikrein from the blood into the urine, can also contribute to the total amount of excreted urinary kallikrein.