Study Of Several Envirmental Factors On Their Mechanisms In Controling Skeletal Muscle Glycogen Biosynthesis

The motivation of this study is to exhibit the biochemical basis for the enhanced exercise performance by endurance training and high-intensity intermittent training , as well as by the supplementation of creatine and glutamine. Based on recent advances in the field of glycogen biosynthesis, we investigated the above mentioned factors of their effects on and mechanisms in regulating muscle glycogen biosynthesis, and, in the meantime, made a primary study of the mechanisms of muscle glycogen supercompensation.Adult male SD rats were used as research subject, orthoganal design method was adopted to arrange the experimental procedure, exercise styles were endurance swim training and weight-loaded high-intensity intermittent swim training, creatine and glutamine were given by irrigation. After 2 weeks of exercise training and tonic supplementing, rats were made to perform a glycogen-depletion exercise, and the target parameters were tested at different time point during recovery period. Some rats were scheduled rest after training(do no glycogen-depletion exercise) till to be killed. Parameters chosen to be tested including muscle macroglycogen(MG), proglycogen (PG), glycogen synthase(GS) activity, glucose transport capacity with and without insulin stimulation, glycogenin(GN) and a -actin gene expression.It was found in the present study that endurance training has the potential to increase muscle glucose transport during 6-24 hours after depletion exercise, and insulin-stimulated glucose transport at rest after endurance training was significantly increased, high-intensity intermittent training has no remarkable effect on insulin-stimulated skeletal muscle glucose transport in rest state, but the transport ability 1 hour after glycogen-depletion exercise was dramaticly increased; Total GS activity in endurance trained rats was significantly increased while GS activity ratio (i/i+d) was significantly decreased at both 1 hour and 24 hour point after depletion exercise; There was no obvious change of GS activity ratio in high-intensity intermittent trained rats during the whole recovery period, and the total GS activity was significantly higher than that of sedentary rats only after 24 hours recovery from depletion exercise; High-intensity intermittent training prior depletion exercise made muscle GN gene expression increased with extremely significant importance during recovery, and the high-level expression maintained from 6 hour point after exercise till to 24 hour point. Endurance training markedly increase GN gene expression as well, but the extent was less and the duration was shorter than that of high-intensity intermittent training rats; Both endurance training and high-intensity intermittent training rats got a more higher muscle MG and/or PG and total glycogen accumulation than that of sedentary rats 24 hours after depletion exercise in the case of no CHO was supplemented , but the real content is almost as same as that of just training rats without a bout of glycogen depletion exercise, indicating that no apparent glycogen supercompensation was achived; Glutamine supplementation significantly increase skeletal muscle glycogen content of rats at rest status, but the normal and insulin-stimulated muscle glucosetransort were not affected; Creatine supplementation has no evident effect on glycogen accumulation, although insulin-stimulated glucose transport was increased significantly. This means that glucose transport capacity was not a key determinant for glycogen accumulation under normal diet and training situation; Ingestion of creatine or glutamine for 2 weeks prior glycogen depletion exercise exert no rule in glucose transport, GN gene expression, GS activity, and muscle glycogen resynthesis rate and amount during recovery from depletion exercise, but the interactions between endurance training and glutamine, high-intensity intermittent training and creatine, and endurance training and high-intensity intermittent training, were all capable of increasing muscle glycogen resynthesis significantly.