Plasma thromboplastic component

The effect of NaCS on all coagulation factors (I—XII) is at least the same as that of heparin. In fact NaCS inhibits the action of the anticoagulant factor VIII (anti-thermophilic globulin) much more effectively than heparin. Therefore, it may be concluded that NaCS acts mainly on factor VIII and partly on factor IX (plasma thromboplastic component) the latter was found to be suppressed by heparin. 

Other Factors. There is little information on the changes in other components of the blood-clotting system in scurvy. Barkham and Howard (B14) have produced evidence that plasma thromboplastic factors and the Factor VII, which are known to be involved in blood clotting (B31), are low in the blood serum and plasma of scorbutic guinea pigs. No abnormality was observed in the clot retraction of scorbutic animals. Small increases (BI4) and decreases (A4) in the number of blood platelets have been reported. 

The antihemophilic globulin, the factor absent from the blood in the best-known hemophilia, combines stoichiometrically with a platelet thromboplastic factor, and the two compounds act like precursors, yielding a product itself a precursor. For thromboplastin, the product is prothromboplastin. The platelet thromboplastin component acts like a catalyst consequently, its concentration does not change during the reaction. The prothromboplastin combines with another compound called the plasma-accelerating globulin to yield a new product, namely, thromboplastin. 

Thus, if the water-soluble fraction is absorbed on tricalcium phosphate and then centrifuged, the supernatant contains a platelet factor referred to as factor I. The tricalcium phosphate pellet contains another factor called factor II, which can be eluted with 0.2% m sodium citrate. Factor II accelerates the conversion of fibrinogen to fibrin by thrombin. Factor III has thromboplastic activity and reverses the anticoagulant effect of heparin, and platelet thromboplastin, or factor IV, reacts with plasma components on active thromboplastin. At least two other factors have been described in platelets—serotonin and fibrinogen that coagulates under the influence of thrombin. Available evidence suggests that fibrinogens in plasma and pate-lets are identical. 

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