不同月龄和部位乌珠穆沁羊AMPK活性与肉品质的关系

为研究乌珠穆沁羊不同生长阶段、不同骨骼肌一磷酸腺苷激活蛋白激酶（adenosine monophosphate-activated proteinkinase,AMPK）活性、糖酵解相关指标和肉质相关指标的内在变化规律，选取3、6、9月龄乌珠穆沁羊背最长肌、股二头肌和腰大肌，分别测定其AMPK活性、肌糖原含量、乳酸含量、己糖激酶（hexokinase,HK）活性、pH值、剪切力和色泽等指标。结果表明：AMPK活性升高时pH24 h值、红度值（a*）明显下降，并呈显著负相关（P<0.05）；剪切力随着月龄增大而降低（P<0.05），腰大肌黄度值（b*）最大，背最长肌b*最小，腰大肌a*变化规律与b*相同，股二头肌与背最长肌a*变化规律与b*相反；同一部位肌糖原含量与月龄呈显著正相关（P<0.05），背最长肌最大，股二头肌最小（P<0.05），乳酸含量变化规律与肌糖原含量总体相同；HK活性与月龄呈正相关（P<0.05），腰大肌最大，股二头肌最小（P<0.05）,AMPK活性随着b*、肌糖原总体含量、6月龄与9月龄乳酸和HK活性升高呈现显著上升趋势（P&l...

Relationship between Adenosine Monophosphate-Activated Protein Kinase (AMPK) Activity and Meat Quality of Three Different Muscles of Ujumqin Sheep Slaughtered at Different Ages

This study aimed to investigate the pattern of changes in the activity of adenosine monophosphate-activated protein kinase (AMPK), glycolysis indicators and meat quality of different muscles from Ujumqin sheep during growth. The Longissimus dorsi, Biceps femoris and Psoas major of Ujumqin sheep slaughtered at 3, 6 and 9 months of age were measured for AMPK activity, muscle glycogen content, lactic acid content, hexokinase (HK) activity, pH, shear force and color. The results showed that AMPK activity had a significant negative correlation with pH24 value and redness value (a*) (P < 0.05). Shear force significantly decreased with increasing slaughter age (P < 0.05). The yellowness value (b*) of Psoas major was largest, while that of Longissimus dorsi was smallest. For Psoas major, the pattern of change in a* was the same as that of b*, while the opposite was observed for Longissimus dorsi and Biceps femoris. A significant positive correlation between muscle glycogen content and slaughter age existed for each of the muscles. Muscle glycogen content was highest in Psoas major and lowest in Biceps femoris. The pattern of change in lactic acid content was the same as that of muscle glycogen content. A significant positive correlation between HK activity and slaughter age existed for each of the muscles. The HK activity of Psoas major was largest, while that of Biceps femoris was smallest. AMPK activity significantly increased with increasing b* and muscle glycogen content, and with increasing lactic acid and HK activity for the slaughter ages of six and nine months (P < 0.05). High AMPK activity could stimulate the key glycolysis-related enzymes during phosphorylation, HK, phosphofructokinase (PFK) and pyruvate kinase (PK), resulting in a rapid pH decline, an increase in lactic acid content, the transformation of aerobic respiration to anaerobic respiration, an increase in shear force and consequently a decrease in tenderness and cooking yield, indicating that changes in AMPK activity affect postmortem glycolysis and meat quality.