A Unique Pathway for the Plasma Elimination of α₂-Antiplasmin-Protease Complexes in Mice

Summary

Radiolabeled α₂-antiplasmin cleared slowly from the circulation of mice. Complex formation with either plasmin or trypsin resulted in a significant increase in the plasma elimination rate of the protease inhibitor. Approximately 20 min and 14 min were required for 50% of the injected α₂-antiplasmin-plasmin and α₂-antiplasmin-trypsin to clear from the circulation, respectively. Significant competition was observed when radiolabeled α₂-antiplasmin-plasmin was cleared in the presence of a large molar excess of unlabeled α₂-antiplasmin-plasmin. α₁-Antitrypsin-trypsin failed to compete with radiolabeled α₂-antiplasmin-plasmin even when present at 2000 fold molar excess. Organ distribution studies localized the major site of α₂-antiplasmin-plasmin clearance in the liver. Microscopic autoradiography data suggested that the cell responsible for the clearance pathway was the hepatocyte.

Keywords

α₂-antiplasimn - α₂-antitrypsin - Protease inhibitor - plasmin(ogen) - Clearance

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