Alterations in erythrocyte survival parameters in rats after 19.5 days aboard Cosmos 782

Rats were subjected to 19.5 d of weightless space flight aboard the Soviet biosatellite, Cosmos 782. Based on the output of 14CO, survival parameters of a cohort of erythrocytes labeled 15.5 d preflight were evaluated upon return from orbit. These were compared to vivarium control rats injected at the same time. Statistical evaluation indicates that all survival factors were altered by the space flight. The mean potential lifespan, which was 63.0 d in the control rats, was decreased to 59.0 d in the flight rats, and random hemolysis was increased three-fold in the flight rats. The measured size of the cohort was decreased, lending further support to the idea that hemolysis was accelerated during some portion of the flight. A number of factors that might be contributory to these changes are discussed, including forces associated with launch and reentry, atmospheric and environmental parameters, dietary factors, radiation, and weightlessness.