Restraint adaptation and altitude tolerance in the rat

¹ U.S. Naval School of Aviation Medicine, Naval Aviation Medical Center, Pensacola, Florida

Sixty-four adult male, albino Wistar rats were divided equally into two groups. Members of one group were subjected to the stress of light restraint for 1 week to produce adaptation to this stress. The other group was not restrained and served as controls. For the altitude tolerance studies both groups were further divided into restrained and nonrestrained animals which were simultaneously exposed to an altitude of 33,500 feet. Both the restrained and nonrestrained restraint-adapted animals showed significantly longer survival times than the corresponding nonadapted rats. Restraint adaptation, however, did not prevent the earlier deaths of the restrained as compared to the nonrestrained animals. The possible physiologic mechanisms involved are discussed.