Saliva and Coagulation of Blood

Abstract

Following the observation that saliva markedly decreases the coagulation time of the blood, 1 studies were made to investigate the specificity of this substance. In our previous work we showed that human saliva collected from the mouth hastens the coagulation of dog, bovine, and human blood.

Dog saliva drawn from the cannulated Wharton's duct has the same accelerating effect, a fact also noted with bovine saliva. With a recalcification time of 6' 15″, 1 cc. of bovine saliva added to 3 cc. of plasma gave a coagulation time of 4' 40″, a reduction of 25%. The coagulant in saliva is, therefore, non-specific either in regard to its source or the source of the blood. This fact is strikingly manifest in the case of hemophilia. Hemophiliac blood, whose inability to clot is attributed both to a delay in the rupture of platelets to yield “tissue extract” and to a delay in the rate of conversion of prothrombin to thrombin, can be readily clotted by the addition of small amounts of saliva, either his own or that of normal individuals. In one individual, who had a clotting time of over 2 hours, the addition of 1 part saliva to 4 parts of his blood gave a solid clot in 3 minutes. Using the same volumes, but diluting the saliva 1 :100 with 0.9% NaCl, the clotting time was 7 minutes with a normal retraction at the end of 45 minutes.

Similar to the effect of any injected animal secretion, a fall in blood pressure with an accompanying hyperpnoea was observed when 5 cc. or human saliva was injected intravenously into an etherized dog. The effect is quickly lost, and the pressure and respiration return to normal, whereupon the same effects may be elicited by repeating the injection.