THE BLOOD CALCIUM AND THE CALCIUM FACTOR IN BLOOD COAGULATION

Abstract

Having summarized modern views on the distribution of Ca in the blood and its physical state in serum, the author reviews data bearing on the relation of Ca to serum proteins, and to coagulant and anticoagulant factors. He concludes that "ionised Ca is essential for the formation of the coagulant factor (thrombin) from its inactive precursors in the blood and tissues. Whether or not we can subscribe to the attractive possibility that thrombin is a colloidal Ca-cephalin protein compound is still an open question, and the exact mechanism of the fibrinogen-thrombin interaction has not been elucidated. The ''decalcifying'' anticoagulants appear to act not only by the simple depression of Ca ionisation but also in a more complex manner involving a splitting-off of Ca from its colloidal combinations, with the additional possibility that the oxalate, etc., may itself enter into union with the plasma colloids. The inability of Ca salts to clot heparinised, hirudinised, ''peptone,'' and other similar anticoagulant bloods demonstrates that these preservers of plasma fluidity act in some other manner than on the Ca mechanism." Ferguson suggests that in platelet lysis Ca changes the colloidal properties of the platelet surface in a way that favors "osmotic imbibition.".