Calcium and Coagulation of Blood

Abstract

Vines 1 called attention to the fact that it requires about 3 times the amount of oxalate to prevent the coagulation of blood than would be expected from the total amount of calcium in the blood. This was confirmed by Loucks and Scott. 2 Vines also called attention to the fact that on recalcifying coagulation occurred before all the oxalate was neutralized. Vines used small amounts of blood and used a biological method for calcium determination and his determinations of the amount of fibrin formed are only relative. It was felt that it was desirable to repeat some of the recalcifying work using larger amounts of plasma. The calcium determinations were made by the method of Kramer and Tisdall 3 while the fibrin formed, was washed, dried and weighed. Dogs that had been anesthetized with nembutal were the source of the blood used.

In a number of cases the amount of oxalate necessary to prevent coagulation was determined and then by recalcification of samples of plasma which had not clotted to see if they would clot at the same deficiency of calcium. Samples of plasma from 15 to 150 cc. were used in these experiments but for comparison all figures are given as if 100 cc. had been used. In all cases a sample of blood was permitted to clot and the calcium estimated in the serum. Loucks and Scott 2 showed the difference in calcium between plasma and serum was within limits of experimental error. To prevent evaporation while centrifuging the centrifuge tubes were always capped with a rubber membrane (Collins and Scott 4 ). All the recalcifying experiments were done at room temperature.