[Morphologic changes in the lungs of rats after a flight aboard biosatellite "Cosmos-936"].

Lungs of 20 rats flown aboard Cosmos-936 for 18.5 days and sacrificed within 5-13 hours (8 weightless and 4 centrifuged rats) and 25 days (4 weightless and 4 centrifuged rats) after recovery were studied histologically. An identical number of lung specimens were withdrawn from rats of synchronous and vivarium controls. Lungs of the flight rats did not show any pathological changes or morphological signs of prolonged congestion, thus indicating the lack of hypertension in pulmonary circulation. Lungs of the flight rats exhibited an increased leukocyte count, which was more marked in the weightless rats killed 8-13 hours postflight. The elevation in the count of neutrophilic leukocytes in the flight rats was due to peripheral neutrophilia which is a manifestation of an acute stress-reaction. An exposure of rats to artificial gravity was responsible for a lesser increase in the count of neutrophilic leukocytes.