Effects of Different Na Concentrations on cAMP-Dependent Protein Kinase Activity in Postmortem Meat.

cAMP-dependent protein kinase (PKA) activity regulates protein phosphorylation, with Na playing a crucial role in PKA activity. The aim of this study was to investigate the effects of different Na concentrations on PKA activity and protein phosphorylation level in postmortem muscle. The study consisted of two experiments: (1) NaCl of 0, 20, 100, 200 and 400 mM was added to a muscle homogenate incubation model to analyze the effect of Na concentration on PKA activity, and (2) the same concentrations were added to pure PKA in vitro incubation models at 4 °C to verify the effect of Na on PKA activity. The PKA activity of the muscle homogenate model increased with storage time in groups with different Na concentrations. High concentrations of Na inhibited sarcoplasmic protein phosphorylation. The PKA activity at 24 h of storage and the sarcoplasmic protein phosphorylation level at 12 h of storage in the group with 200 mM Na was lower than that of the other groups. After 1 h incubation, the PKA activity of samples in the 200 mM Na group was inhibited and lower than that in the other Na groups in the in vitro incubation model. These results suggest that the Na concentration at 200 mM could better inhibit PKA activity. This study provided valuable insights for enhancing curing efficiency and improving meat quality.