Abstract
Abstract : Warm- and cold-acclimated rats could withstand prolonged exposure to cold after restriction of food. Their catecholamine excretion rapidly attained maximal values and the animals died in hypothermia. The same happened with warm-acclimated rats whose insulation had been reduced by removal of the fur. Cold-acclimated clipped rats survived in the cold, but their catecholamine response was much more intense than that of intact cold-acclimated animals. These two series of experiments strongly support the view that acclimation to cold is limited by the finite capacity of the organism to produce and/or secrete sufficient amounts of catecholamines to maintain thermal balance. They also emphasize the necessity for coldacclimated animals to reach a new level of acclimation when conditions are changed. The previous degree of acclimation increases the chances to attain that new state of equilibrium by virture of an increased sensitivity of cold-acclimated rats to catecholamines, thus extending the time at which the catecholamine production and/or secretion becomes saturated. The importance of adrenaline as a supplementary hormone of defense against cold is shown by the lower ability of adrenalectomized corticoids maintained rats to support cold exposure under severe conditions. (Author)
Published Version
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