Abstract
The hypocoagulation of blood in hibernating animals is attributed to the decrease in platelets and the presence of anticoagulant factors in the blood. However, the mechanisms are still not well understood. Therefore, we examined the parameters related to the blood coagulation in Syrian Hamsters (Mesocricetus auratus) during the hibernation-arousal cycles. In the functional tests of coagulation using plasma, the delay of the activated partial thromboplastin time (APTT) and the prothrombin time (PT) were detected in the hibernating animals. However, heparin was not detected in the plasma, while the decrease of the antithrombin (AT) III, and the low, but significant amounts of the thrombin-antithrombin III complex (TAT) were detected only in the deep hibernating animals, suggesting the activation of the blood clotting system. Meanwhile in the histopathological examination, both the accumulation of many platelets and tiny fibrin clots were observed in the hepatic central veins and sinusoids only in the hibernating animals. Thus, the acceleration of the blood coagulation system, at least partially, may exist behind the hypocoagulation in deep hibernating animals. [J Physiol Sci. 2007;57 Suppl:S179]
