The Increase of Short-term Heat Exposure Temperature at Extreme Range Decreased Phosphofructokinase-1 Activity and AMPK Phosphorylation in Postmortem Chicken Breast Muscle

Abstract Preslaughter exposure to high ambient temperature could accelerate postmortem glycolysis and impair chicken breast (pectoralis major muscle) quality. However, previous studies indicated that it might be different when the temperature of short-term heat exposure (SHE) raises to extreme range (above 38°C). Therefore, the objectives of this study were to evaluate the effect of SHE in the range of extreme temperatures (36°C, 38°C, and 40°C) on the activity of glycolytic enzymes and AMP-activated protein kinase (AMPK) in postmortem muscles. The activity of key glycolytic enzymes and phosphorylation of Threonine 172 in AMPK α subunit (p-AMPK-α[Thr172]) during early postmortem (0.1, 1, 2, and 4 h) and the muscle pH decline (0.1, 1, 2, 4, and 24 h) were evaluated. SHE did not affect (P > 0.05) glycogen phosphorylase a (GPa) and pyruvate kinase (PK) activity within 4 h postmortem. However, the phosphofructokinase-1 (PFK-1) activity and phosphorylation of AMPK-α[Thr172] decreased (P < 0.05) as antemortem SHE temperature increased from 36°C to 40°C, which could explain the faster pH decline in the 36°C group at 1 h and 2 h postmortem (P < 0.05), and it could be attributed to proteotoxic stress response resulting from extreme heat exposure. Hexokinase (HK) activity was also affected by the SHE temperature (P < 0.05) with the 36°C group having the highest (P < 0.05) activity within 4 h postmortem. The results of the current study, for the first time, indicated that the increase of antemortem SHE temperature at extreme range does not always accelerate the pH decline rate and increase postmortem glycolytic enzyme activity and AMP-activated protein kinase phosphorylation and that the postmortem metabolism is dependent on SHE temperature. Further research is necessary to explore the biochemical basis of this temperature-dependent pH decline, glycolytic enzyme activity, and AMPK phosphorylation.