Chronic intermittent hypoxia versus continuous hypoxia: Same effects on hemorheology?

Although both chronic intermittent hypoxia (CIH) and chronic continuous hypoxia (CCH) have effects on hemorheology, we do not know whether their roles are the same. In this study, we explored the effect of simulated-apnea CIH on hemorheology in experimental rats and compared with the effect of CCH. 45 adult SD rats were randomly divided into the normoxic control group, CCH and CIH groups. CIH rats were given nitrogen and air alternately for 8 hours per day and the experiment lasted for 5 weeks. The control group were placed in the normoxia animal chambers, and the CCH rats were housed in the same chambers which were continuously given normobaric hypoxia (FiO2 = 10%). After the preparations, the blood samples were taken and the hemorheology were determined. Compared with control group, the whole blood apparent viscosity, plasma viscosity, hematocrit, erythrocyte aggregation index and electrophoresis index, platelet aggregation rate and fibrinogen significantly increased in CIH group and CCH group. The whole blood viscosity, plasma viscosity, hematocrit and fibrinogen values were much higher in CCH group than in CIH group. However, there was not significantly difference in RBC deformation index or rigidity index among the three groups and no significantly differences were found in the effects on RBC rheological property between CIH and CCH. Our results suggest that intermittent hypoxia and continuous hypoxia increase whole blood viscosity, impair the functions of red blood cells and promote the platelet aggregation in model rats. Moreover, CCH had a greater effect on blood rheology than CIH.