Morphometrical evaluation of myocardium from rats flown on biosatellite Cosmos-1887.

The myocardium of rats kept on the biosatellite Cosmos-1887 for 13 days was morphometrically examined at the cellular and subcellular levels. It was found that weightlessness causes in the heart muscle cells atrophy of the muscle fibers, thinning of the sarcomeres a decrease in the relative volume and number, a change in the shape of mitochondria and an increased accumulation of glykogen. These changes may be attributed to the muscle fibers atrophy and metabolic disturbances. The presented results indicate that weightlessness produces changes in the continuously working myocardium.