[EFfect of exposure to cold on growth characteristics and anabolic processes developing rats]

Rats growing under cold stress conditons during the first month of their postnatal life attain higher body weight, muscle mass, heart, brain, thymus and suprarenals as compared to control animals. The increase in these indices is paralleled by higher protein and glycogen contents of the skeletal muscles and as well as by more intense incorporation of C-14-uridine and H3-lysine into total RNA and proteins of muscles, brain and thymus. Experimental rats exhibit also higher content of lysozymes and leucocytes (neutrophils and eosinophils) in the blood, and higher level of ascorbic acid in the suprarenals. Economization of energy expenditures at rest together with the changes mentioned indicate the increase of the adaptive capacities and total nonspecific resistance of rats developing under cold stress conditions.