Open AccessIn vitro and in vivo correlation of clotting protease activity: Effect of heparin
Author(s) -
Sanford N. Gitel,
Ronald C. Stephenson,
Stanford Wessler
Publication year - 1977
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.74.7.3028
Subject(s) - thrombogenicity , thrombin , heparin , antithrombin , proteases , in vivo , coagulation , factor ix , chemistry , tissue factor , pharmacology , thrombosis , biochemistry , immunology , medicine , biology , platelet , enzyme , microbiology and biotechnology
The thrombogenicity of three highly purified proteases (thrombin, activated Factor X, and activated Factor IX) was determined quantitatively in an animal model. The minimal amounts required to produce a standard score 4 thrombus were 1.1 nmol for thrombin, 0.12 nmol for activated Factor X, and 0.018 nmol for activated Factor IX. After the administration of heparin at 5, 10, and 20 units/kg in rabbits, the thrombogenicity of each of these proteases decreased progressively. The heparin-induced inhibition of thrombosis decreased in the order, activated Factor IX > activated Factor X > thrombin at each heparin concentration. These differences were statistically significant. Thesein vivo data provide support for the following hypotheses originally developed fromin vitro experiments: (i ) activation of the blood coagulation system, which proceeds through a cascade mechanism, incorporates biochemical amplification; (ii ) the inhibition of activated Factor IX by antithrombin III in the presence of heparin is an important reaction in the prevention of thrombosis; (iii ) less heparin is required to inhibit thrombosis prior to thrombin generation than afterward; (iv ) an increase in the reactivity of antithrombin III reflects a decreased tendency to thrombosis while a decrease in this reactivity reflects an increased tendency to thrombosis.