EFFECT OF THYROIDECTOMY, ADRENALECTOMY AND BURNING ON THE URINARY NITROGEN EXCRETION OF THE RAT MAINTAINED IN A COLD ENVIRONMENT1

Abstract

In a cold environment (1.5[degree]C) rats excreted 77% more N in the urine than at normal room temp. (25[degree] [plus or minus]2[degree]). When the food intake in the cold was doubled, the urinary N was increased further to about 2.3 times its original value. Growth as measured by increase in body wt. was slow, however. After exposure to cold a marked increase in urinary N occurred in both thyroidectomized and DCA-injected adrenalectomized rats. The effects of a mild burn and of exposure to cold on urinary N excretion were cumulative, and under the conditions of the expts. appeared to be greater than would be expected from the sum of the N losses due to the 2 stimuli acting independently. The thesis that a different mechanism is involved in the increased protein catabolism after burns and during exposure to cold is discussed.