Coagulation of Oxalated Plasma without Calcium Following Neutralization of Heparin by Toluidine Blue

Abstract

UNDER physiological conditions, calcium is necessary for the coagulation of blood, because with thromboplastin it brings about the change of prothrombin into thrombin. But the true role of calcium ions has not hitherto been understood. On the other hand, this change is inhibited by heparin in connexion with a plasmatic co-factor, which was determined as an acid-soluble albumin¹. The anti-coagulating influence of heparin is specifically inhibited by toluidine blue². We have used this property of toluidine blue to examine the function of the heparin which in normal circumstances is present in the blood. The influence of the physiological amount of heparin on blood coagulation is still under discussion. The complex heparin–plasma co-factor inhibits the action of thromboplastin on the change of prothrombin to thrombin³. We are putting forward the working hypothesis that the interaction between the heparin complex and thromboplastin of plasma is the cause of the fluidity of blood in the vessels, and that calcium in some way either with a tissue extract or otherwise neutralizes the heparin complex. If this assumption is correct, the toluidine blue will coagulate the decalcified plasma.