Differences in the Effect of Antithrombin on Thrombin Clotting and Thrombin Esterase Activity^[*]

Summary

Following the addition of thrombin to serum, thrombin clotting activity rapidly disappears. During the first half hour thrombin esterase activity also declines. Subsequently, the thrombin esterase activity remains stable for a long time.

Heparin which, under these circumstances profoundly alters the thrombin clotting-activity, affects the thrombin esterase activity only slightly. Hence serum induced inhibition of thrombin esterase activity is not significantly altered by heparin.

The possible relationship of these findings to the spontaneous resolution of thrombo-emboli is discussed.

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• 11 Supported by PHS Grants (HE 05341 and HE 12324).