Synthesis of Tissue Glycogen in Rats Prefed Diets With Added Glycine

¹ From the Department of Biochemistry, University of Oregon Medical School, Portland, Oregon

The maintenance of liver and muscle glycogen after the stress of swimming in cold water, followed by various lengths of recovery periods, has been studied in rats prefed diets with and without added glycine. Rectal temperatures reached a minimum of 33.3°C and returned to normal in about 3 hours in both groups. Though the differences were not great, muscle glycogen was significantly higher in glycine-fed animals at the end of the stress and at all times studied during the recovery period except at 5 hours. Resynthesis started earlier in these animals during recovery. Glycine-fed rats showed markedly higher liver glycogen levels after stress and at all times studied during the recovery period. Redeposition of liver glycogen started earlier in these animals and after 3 hours of recovery the levels had returned to those found immediately following the stress. The control fed rats synthesized much less liver glycogen during the recovery period. The data agree with the postulate that prefeeding diets high in glycine stimulates glycogenesis in rats during an ensuing stress.