Effects Of AMPK Activity Regulation On Energy Metabolism Of Postmortem Beef In Different Muscles With Different Temperature Treatments

With the development of our society,the demand of high quality meat is increasing a lot.The energy metabolism process in postmortem muscle is essential to the meat quality,especially the glycolysis process.Both of the rate and extent of glycolysis can affect the meat quality.AMPK(AMP-activated protein kinase)may play an important role in the glycolysis of postmortem muscle.It may be an effective target to control the meat getting inferior.Lots of studies about AMPK have been carried out,but few focused on the beef muscle postmortem.In this study,four head of Luxi crossed Simmental cattle were selected in a local commertial beef slaughtering plant,two muslecs(psoas major and longissimus dorsi)were removed from the carcasses before the carcasses entered into the chilling rooms.Both muscles were immersed in AICAR and Compound C immediately after the muscles removed.All the samples were kept at at three different temperatures(4?,14?,20?)and different time(0.5h,1.5h,3h).AMPK activity,hexokinase activity,pyruvate kinase activity,lactic dehydrogenase activity,creatine kinase activity,acid phosphatase activity,lactic acid content,pH value,glycogen content of all samples with different treatments were measured accordingly.The main results are as follows:1.AICAR can increase the activity of AMPK,pyruvate kinase,hexokinase and lactic dehydrogenase.The glycogen content and pH value decreased faster than control group.The accumulation of lactic acid is accelerated by AICAR.Compound C showed an opposite effect.2.AMPK activity in PM of three treatment groups(activator group,control group and inhibitor group)was significantly higher than LD(P<0.05),the activity of glycolysis enzymes and lactic acid content in PM were all significantly higher than LD(P<0.05),but PM has lower glycogen content and pH value.It indicated the glycolysis rate was faster in PM than that in LL.3.The interaction of AMPK activity level(activator group,control group and inhibitor group)and muscle cuts(PM & LL)significantly affected AMPK,hexokinase,pyruvate kinase and lactic dehydrogenase activity,lactic acid content and pH value.The inhibitor(Compound C)was more effective in PM than that in LD.4.The interaction of AMPK activity level(activator group,control group and inhibitor group)and treatment time significantly affected AMPK,hexokinase and pyruvate kinase activity,lactic acid content and pH value.Compared with 0.5h and 3h,AMPK was more effective when the samples were immersed for 1.5h.5.The interaction of AMPK activity level(activator group,control group and inhibitor group)and different treatment temperatures significantly affected AMPK and lactic dehydrogenase activity.In contrast with 4? and 20?,AICAR showed the most obvious effect at 14?.In this study,AICAR and Compound C were used as AMPK activator and inhibitor,respectively.It indicated that AMPK indeed played a key role in the glycolysis of postmortem beef,through effecting on the activity of HK,PK and LDH.