Upregulation of coagulation pathway and enhanced platelet activity in hypoxia-exposed rat blood.

To investigate the effects of chronic hypoxia on platelet characteristics and overall coagulation function, and to elucidate the mechanisms underlying high-altitude-induced blood system disorders. Rats were exposed to chronic hypoxic conditions. Platelet counts were measured using routine blood analysis. Plasma levels of platelet activation markers (P-selectin and sCD40L) were quantified by ELISA. A label-free quantitative proteomic approach was employed to identify alterations in the platelet coagulation cascade proteome, with key findings validated by western blotting. Coagulation function was assessed via prothrombin time (PT) and thromboelastography (TEG). Chronic hypoxia resulted in a significant decrease in platelet count compared with controls. This was accompanied by a significant increase in plasma markers of platelet activation, P-selectin, and sCD40L (P < 0.05). Proteomic analysis revealed substantial alterations in the expression of coagulation-related proteins in platelets. These changes were confirmed by western blot, which showed significant upregulation of key coagulation factors, including F2, F9, F10, and F12. Consistent with these molecular changes, functional assays demonstrated a significant prolongation of PT and a marked reduction in overall coagulation function as measured by TEG, evidenced by a prolonged R-time and decreased α-angle and maximum amplitude values. Chronic hypoxia induces a state of platelet activation and thrombocytopenia but, paradoxically, leads to an overall net reduction in coagulation function. This dysfunction is linked to significant alterations in the expression of multiple coagulation factors within platelets, suggesting a complex regulatory mechanism beyond simple platelet counts that may contribute to the bleeding diathesis observed in high-altitude environments.