Adenosine monophosphate-activated protein kinase status modulates kinetics of post-mortem pH decline and meat quality in pig Longissimus muscle

摘要

AMP-activated protein kinase (AMPK) is a sensor of cellular energy status involved in regulation of glycogen metabolism and it influences meat quality by modulating post-mortem (p.m.) energy metabolism. This study aimed at evaluating the relationships between AMPK activity in the pig Longissimus muscle (LM) and the kinetics of p.m. pH decline. A total of 117 pigs exhibiting a high variability in muscle glycolytic potential (GP) (84 up to 212 μmol lactate/g fresh muscle) were used. Samples of LM were taken just after exsanguination (TO) to represent the in vivo situation, and then at 30 min (T30) and 24h p.m.. GP, pH at T30 (pHl) and at 24h (pHu) were determined. Total AMPK and its level of activation (pAMPK/total AMPK) were quantified at both TO and T30 by immunoblotting. AMPK activation at T30 was positively correlated with pHu (r=0.40, p<0.001) and negatively with GP (r=-0.42, p<0.001) and pHl (r=-0.23, p=0.01). A stepwise regression method (R~2=0.52, p<0.001) identified GP, pHl and pAMPK/total AMPK at T30 as the best predictors of pHu. Phosphorylation status of AMPK was also involved in the determination of pHl, but the model explained less variability of this trait (R~2=0.22, p<0.001). Moreover, AMPK status at TO and T30 were highly correlated (r=0.69, p<0.001), suggesting that a high in vivo level of phosphorylation of this enzyme could increase the rate and reduce the extent of pH decline. Altogether, this indicates that the control of AMPK activity during the rearing period seems to be an interesting way for modulating pork quality.