|(1.School of Physical Education，Luoyang normal University，Luoyang 471022，China；2.Wenzhou Medical College，Wenzhou 325035，China；3.Beijing Sport University，Beijing 100084，China)
Abstract: The authors probed into functions played by changes of AMPK activity in the degradation of skeleton muscle protein during one time high intensity endurance exercising. Method: let 36 SD rats do a one time treadmill exercise at a slope of 5%, an exercise intensity of 25 m/min, and an exercise time of 60min. Sampling times were before exercising, after 0.5h and 1h of exercising, 1 h, 2 h and 6 h after exercising. The authors measured AMP and ATP molalities by using high efficiency liquid chromatography, changes of AMPK activity in gastrocnemius mus-cle by using isotope technology, and changes of MuRF1 and MAFbx gene expressions in gastrocnemius muscle by using fluorescence quantification PCR technology. Results: 1) from the moment after 0.5 h of exercising to the movement immediately after exercising, AMP molality and the ratio of AMP molality to ATP molality increased (P<0.05); there was no significant difference in AMP molality and the ratio of AMP molality to ATP molality in gastrocnemius muscle between 1 h, 2 h and 6h after exercising groups and the calm group; there was no significant change or difference in ATP molality between various groups; 2) AMPK activity started to increase after 1.5 h of exercising, reached its peak at 2 h after exercising, started to lower at 6 h after exercising but was still higher than that of rats in the control group; 3) there was no significant difference in MuRF1 mRNA and MAFbx mRNA ex-pression volumes between after 0.5h and 1h of exercising groups and the calm group; compared with those of rats in the calm group, MuRF1 mRNA and MAFbx mRNA expression volumes of rats in 1h and 2 h after exercising groups increased by 1.98 times, 3.57 times and 1.95 times 2.55 times respectively, and the differences were very significant (P<0.01); compared with those of rats in the calm group, MuRF1 mRNA and MAFbxmRNA expression volumes of rats in the 6h after exercising group increased, and the differences were significant (P<0.05). The results indicate that in 1-6 h after one time high intensity endurance exercising, the degradation of skeletal muscle protein may be intensified, possibly by MAFbx mRNA and MuRF1 mRNA gene expressions promoted by AMPK activation.
Key words: exercise biochemistry；AMPK；MAFbx；MuRF1 mRNA；protein degradation；rat；AMP