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An attempt was made to determine the manner and extent of compensation to the thermal stresses imposed by the injection of atropine and pilocarpine. Complete thermal balance studies were made on subjects before and after subcutaneous injection of these drugs at two different ambient temperatures. Changes in evaporative rate produced by these drugs are thermally compensated by alterations in convection and radiation and, under some conditions, in peripheral blood flow and metabolism. The compensatory mechanisms are not sufficiently prompt nor large enough to maintain thermal balance immediately after the injection. They persist, however, much longer than does the altered evaporative rate. The 'atropine flush' is a reaction secondary to a reduction in evaporative rate. (Author)

Limited studies by this laboratory of basal metabolic rates of men exposed to cold in an Arctic environment did not reveal any demonstrable change in energy metabolism. In order to determine the effects of varying amounts of cold exposure on thyroid function, studies were carried out on rats using the uptake of radioiodine as a measure of the functional activity of the gland. Male rats were exposed to 4 + or - 0.5 C for periods of from 2 hours through 60 days. A diminished amount of radioiodine was found to be present in the experimental animals at exposure intervals under 6 hours. The amount present at about 6 hours was the same as for the controls and increased after 12 to 24 hours. The increased uptake was most pronounced at 7 to 9 days and gradually returned to control values by 40 days.