The Mechanism of the Action of Saliva in Blood Coagulation

It is well known that the addition of saliva to blood will accelerate its coagulation (1, 2, 7). This property of saliva is not species specific. It has been shown that dog, cat and human saliva will indiscriminately accelerate the clotting of blood obtained from the dog, cat, cow or man (1, 7). Bellis, Birnbaum and Scott (1) noted that while the clotting factor of saliva was stable at 60 " , it was destroyed by boiling at 100 ". Bellis and Scott (2) found that the addition of saliva decreased the co-agulation time of hemophilic blood, and that a similar effect was obtained with peritoneal and cerebrospinal fluids. The present investigation was undertaken to determine the function of saliva in the coagulation mechanism and to investigate the nature of the active material. The results obtained indicate that saliva contains a factor which acts like the thromboplastic material present in blood platelets, brain and lung tissues and that it probably is protein in nature. EXPERIMENTAL. The reagents employed in this investigation were prepared as follows: Plasma-from beef blood obtained by the addition of 0.2 per cent potassium oxalate. Prothrombin-prepared according to the method of Mellanby (8). The product was not activated by calcium ions alone when incubated for the maximum length of time of the experiments. Fibrinogen-obtained by repeated precipitation with sodium chloride as described by Eagle (3). &&z-human saliva was collected by first rinsing the mouth with saline and the chewing of paraffin to stimulate the flow. Samples were used within a few hours of collection. Calcium chloride-O. 025M solution. Thromboplastin-a fresh saline extract of blood-free calf-brain. The clotting mechanism may be separated into two well-recognized stages; 1, the formation of thrombin, and 2, the formation of fibrin from fibrinogen. The first step in analyzing the role of saliva was to determine which of these two stages was influenced by the presence of saliva. The following observations show that saliva has no important action on fibrinogen but that it is active in the formation of thrombin. When fresh, filtered saliva is added to purified fibrinogen, no clot 108