Summary
Anti-plasmin and anti-urokinase activity of plasma was investigated with a method
using preformed 131I-labelled clots. The inhibition of plasmin by plasma was found to be produced partly
by direct and partly by slow progressive inactivation, while the results did not support
the supposition that the anti-plasmin-plasmin complex is reversible in the presence
of fibrin.
It was found that thrombocytes contain very little anti-plasmin, and that heparin
in a concentration as occurs during anticoagulant therapy does not influence the anti-plasmin
nor the anti-urokinase activity of the plasma.
The results provide evidence that urokinase and blood activator are not identical
substances and it is concluded that estimation of the anti-urokinase activity will
not produce an index for the presence of an inhibitor of the blood activator.