Associations among adenosine monophosphate-activated protein kinase, glycolysis, muscle characteristics, and apoptosis in postmortem bovines longissimus muscle

Abstract

The Musculus longissimus thoracis muscle of twenty crossbred cattle was used to investigate the activity of calcium-regulated protein kinase kinase (CaMKKβ), adenosine monophosphate-activated protein kinase (AMPK), glycolysis pathway, and apoptosis during 7 days postmortem maturation. Results showed that CaCl2 significantly increased the activity of CaMKKβ and AMPK. Meanwhile, the activation of AMPK increased the activity of rate-limiting enzymes in glycolysis (lactate dehydrogenase and pyruvate kinase), and accelerated the speed of postmortem muscle maturation. Besides, CaCl2 altered the properties of myofibrillar, affected the intramuscular environment, and induced postmortem apoptosis. Our finds indicate that CaCl2 activates AMPK, accelerating the glycolysis process and increasing mitochondrial ROS level, which was an upstream event of apoptosis. Muscle samples treated with CaCl2 had better tenderness, probably due to the degeneration of myofibrillar proteins and the occurrence of apoptosis, which may have contributed to the increased AMPK activity and accelerated glycolysis.