The elimination in dogs of trypsin-alpha-macroglobulin complexes inactivated by the Kazal or the Kunitz inhibitor.

The elimination of trypsin-alpha-macroglobulin complexes and similar complexes with the trypsin inactivated by low-molecular weight inhibitor was studied in anesthetized dogs. The complex was inactivated either by the Kazal (pancreatic secretory trypsin inhibitor, PSTI) or the Kunitz inhibitor (Trasylol BE). The inhibitors were labelled with 125I and in the case of the trypsin-alpha-macroglobulin complex the trypsin was labelled with 125I. All of the inactivated complexes exhibited a half-life of about 5 min in the dog. The elimination in plasma was exponential until 80 - 85% of the initial dose was cleared in 30 min and nearly negligible thereafter as seen by radioactivity measurements. Simultaneously increasing amounts of dialyzable radioactive substances with a lower molecular weight than the inhibitors were recovered in the urine. No significant differences in the elimination of trypsin-alpha-macroglobulin complexes were detected in plasma or in the urine before and after inactivation with the Kazal inhibitor (PSTI) or the Kunitz inhibitor (Trasylol BE).