Blood coagulation and fibrinolysis in rats after hypokinesia and hyperthermia.

Coagulation and fibrinolysis were studied in rats exposed to hypokinesia (HK) obtained by including rats (for 1, 2 and 3 weeks) in small cages designed to limit their movements, permitting only spontaneous feeding (a method widely used for mimicking space flight conditions). The number of thrombocytes, the Quick time, the Howell time and the euglobulinlysis time (ELT) decreased after 1 and 2 weeks of HK; however, after 3 weeks, the parameters of coagulation approached normal control levels, while ELT was still significantly under the control values. An increased blood level of corticosterone in animals subjected to HK suggested that changes observed in the blood coagulation could be linked with it. After exposing rats to heat, similar changes were noticed, i.e. thrombocytopenia and an increase in the speed of coagulation and fibrinolysis. When hyperthermia was induced in hypokinetic animals (after 1 and 2 weeks of HK), the association of exposure to HLK and heat was not followed by a cumulative response.