[Comparative analysis of the effect of alpha-thrombin and trypsin on the state of the anticoagulating system]

The reflex response of anticoagulating system was studied in perfusion of humorally isolated sinocarotid area with trypsin and alpha-thrombin in rabbits with intact neural connections. Trypsin (1.5 and 3.8 microM) does not induce a reflex release of heparin and plasminogen activator into the blood flow whereas alpha-thrombin (0.5 microM) activates the anticoagulating system which is evident from elongation of the recalcification period, augmentation of total fibrinolytic activity and non-enzyme fibrinolysis of the blood plasma. The level of plasminogen activator sharply rises in the blood with no significant augmentation of the plasmin activity. The data obtained suggest that the specific nature of thrombin in due to the area of high-molecular substrates binding rather than proteolytic activity. Chemoreceptors of the sinocarotid area fail to respond to thrombin after trypsin perfusion which suggests failure of the receptor apparatus after contact with trypsin.