Effects of chronic hypoxia on platelet production in mice.

Platelet production, platelet count, and RBC count were measured in mice after enclosure in silicone-rubber membrane cages. Results indicate that enclosing C3h mice in hypoxia chambers for 2 weeks caused increased RBC count and decreased platelet production leading to thrombocytopenia. Splenectomized C3H mice placed in hypoxia chambers also showed decreased platelet count and platelet production when compared to splenectomized ambient air control mice. Injection of rabbit anti-mouse-platelet serum (RAMPS) caused an immediate thrombocytopenia with rebound-thrombocytosis 5 days later in normal mice and mice transfused with RBC. However, mice exposed to hypoxia and given RAMPS injections exhibited marked inhibition of platelet production. Although indirect, these findings suggest that hypoxia-induced erythrocythemia causes thrombocytopenia by stem cell competition between the erythroid and megakaryocytic cell lines.