Decreased platelet level in peripheral blood of mice by microgravity.

It is reported that the stay in the space develop anemia, throbocytopenia, and altered function and structure of red blood cell. The mechanism of these abnormalities was not clarified yet. TPO has been shown to stimulate both megakaryocyte colony growth from marrow progenitor cells and the maturation of immature megakaryocyte to form functional platelet. This process include massive cytoskeletal rearrangement, such as proplatelet formation and fragmentation of proplatelet. Our previous reports (Fuse and Sato, 2001, Fuse et al, 2001) showed an inverse relationship between decreased platelet count and increased TPO concentrations in peripheral blood of mouse was induced by parabolic flight (PF). We have studied which gravity change during PF involved this phenomenon.