Effect of proteases on plasminogen activator release from isolated perfused dog leg.

Abstract

<h2>Abstract</h2> The present study was undertaken to determine which proteases could induce the release of plasminogen activator from isolated perfused dog hind leg. The proteases tested were thrombin, trypsin, chymotrypsin and factor Xa which show restricted specificities of various kinds, and papain which shows a broader specificity. Thrombin at concentrations of between 2 × 10⁻⁸ M and 6 × 10⁻⁷ M released plasminogen activator dose-dependently. Trypsin released plasminogen activator as strongly as thrombin. On the other hand, chymotrypsin exerted little effect on plasminogen activator release even at 5 × 10⁻⁶ M, and factor Xa at concentrations of between 10⁻⁷ M and 5 × 10⁻⁷ M showed no activity to release plasminogen activator. The effect of papain on plasminogen activator release was very weak and not dose-dependent. These results indicate that plasminogen activator release from the vessel wall was induced specifically by only particular proteases such as thrombin and trypsin. This suggests that certain arginine residues of the reactive sites on the vessel wall may participate in the release of plasminogen activator by proteases.