Plasmin inhibitory effect of rat tissues: comparison with antiplasmin activity of plasma

Plasmin inhibition by rat tissue extracts was compared with rat plasma plasmin inhibition. Nine different tissues were extracted with an acid acetate-buffer (lung, heart, brain, adrenal, aorta, skeletal muscle, spleen and liver) or with KSCN-buffer (kidney), and antiplasmin activity was evaluated by a spectrophotometric method. All tissue extracts inhibited plasmin dose-dependently; the amount of plasmin inhibited by a fixed amount of extract depended upon the tissue. In rat plasma, antiplasmin activity was acid-labile, but acid treatment did not affect the plasmin inhibitory effect of tissues extracts.