General and Specific Characteristics of Physiological Adaptations

Abstract

Adaptations (adaptates) were induced when individual rats were exposed to a particular stressor. They are modifications of function that outlast the stressor. Quantitative data chiefly concerned the effects of prolonged exposures to cold air, to simulated altitude, or of repeated administration of cold air, low oxygen, water, sodium chloride or sucrose. Adaptations to several stressors could be compared kinetically. Some adaptates were alike in their courses of development; but varied latencies, rates and directions of modifications were also found. Most manifestations of adaptation gradually disappeared (deadapted) in the absence of further exposure. The disappearance was usually slower than the development. The initial state of the function measured was reattained. Hence, adaptations were believed to superimpose upon more stable patterns of regulation. The combination of modifications that resulted when a given stressor impinged was found empirically but could not be predicted. The adaptates studied were more often specific to one stressor than general to more than one.