CALCIUM IN THE COAGULATION OF THE BLOOD

Abstract

The clotting time of blood depends on 3 variables: prothrombin, thromboplastin, and Ca. Prothrombin is relatively constant for the blood of any one sp., and thromboplastin can be made a constant by adding an excess. Under these conditions, the effect of Ca as a variable was studied. The removal of ionized Ca by means of Na oxalate does not affect the conversion of prothrombin to thrombin. Coagulation is stopped only when 3 times the calculated amt. of Na oxalate is added. The anticoagulating action of Na oxalate is not instantaneous, but the higher the concn., the faster the inactivating effect. The results can best be explained on the assumption that prothrombin is a Ca compound, and that on treatment with Na oxalate or citrate, an inactive derivative is formed which is however quickly and completely regenerated into prothrombin by recalcification.