[Role of thyroid hormone in cold adaptation. 1. Requirement of thyroxine during the course of cold acclimation as estimated by noradrenaline sensitivity (author's transl)].
The amount of thyroxine required for the development and maintenance of cold acclimation was investigated in the rat. Warm-adapted thyroidectomized rats could not survive at 5 degrees C. When thyroxine was replaced, these rats could survive and responded to noradrenaline with increased oxygen consumption in proportion to the dose of replaced thyroxine. Judged from the amount of thyroxine in thyroidectomized rats necessary to restore noradrenaline sensitivity to the same level as seen in intact controls, 30 degrees C-adapted rats were found to require 3.3 mug thyroxine/100 g b.w./day, while 5 degrees C-adapted rats required only 1.2 mug. It is concluded that the amount of thyroxine necessary to produce cold acclimation is much larger than that for the maintenance of cold acclimation.
D000064:Acclimatization / Q000187:drug effects; D000818:Animals; D003080:Cold Temperature; D004305:Dose-Response Relationship, Drug; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D013961:Thyroid Gland / Q000502:physiology; D013974:Thyroxine / Q000008:administration & dosage / Q000502:physiology*; D013997:Time Factors
D013974:Thyroxine; D009638:Norepinephrine