[The nature of the hypermetabolism and tachycardia in cold adaptation and experimental hyperthyroidism]

The cross circulation method has been used to study contribution of humoral and nonhumoral components to the origin of hypermetabolism (increased level of basal metabolism) and tachycardia under adaptation to cold and experimental hyperthyroidism. Consumption of oxygen, heart rate and rectal temperature have been studied in periods prior to and during the cross circulation. It is shown that under experimental hyperthyroidism contribution of humoral and nonhumoral factors to the origin of hypermetabolism equals 22 and 78%, while that to genesis of tachycardia--44 and 56%, respectively. Under cold adaptation an increase of the basal metabolism level depends on humoral agents by 77% and on changes of the stationary character only by 23%. The nature of adaptation tachycardia is mainly, of the humoral origin (65%).