Effects of Hyperthermia on Blood Coagulation -In vitro Experiments-

Human blood was incubated in the waterbath at various temperature (0•`50•Ž) for various time (5•`90 mm). Then the effect of temperature on several parameters (APTT, PT, fibrinogen, activities of clotting factors, platelet aggregation) were studied. The results were as follows. 1. APTT and PT didn't change below 40•Ž, but they were prolonged significantly at 43•Ž, which was the border temperature for some normal and tumor cells. 2. Prothrombin activity decreased at 50•Ž, and Factor X did at 45•Ž. Fibrinogen was clottable between 0•Ž and 45•Ž, but became to be unclottable at 50•Ž. On the other hand, the changes of fibrin clot strand was observed at 43•Ž and above under scaning electron microscope. 4. Platelets lost their aggregative function at 43•Ž when collagen was used as inducer, at 40•Ž using ADP. From these results, we concluded that 43•Ž might be the critical temperature in blood coagulation system as well as in the case of hyperthermia.