Temporal proteomic response to acute heat stress in the porcine muscle sarcoplasm.

Heat stress (HS) is an important topic in the swine industry, costing hundreds of millions of dollars in economic losses annually, figures that could easily rise in light of global climate change. Muscle biology during HS is particularly important given skeletal muscle's large proportion to the body and its ultimate conversion to meat. Here we report the proteomic changes that occur during acute HS (37°C and 40% relative humidity) lasting 2, 4, or 6 h in the muscle sarcoplasm of growing pigs in comparison with 6 h of thermal neutral (TN; 21°C and 70% relative humidity) conditions ( = 8 per treatment). The red and white areas of the semitendinosus muscle were used to compare the differential effects of HS on oxidative or glycolytic muscles. The results support the hypothesis of proteomic profile differences between the acute HS and TN groups. Altered abundance ( < 0.05) of several proteins occurred in as little as 2 h of HS, affecting metabolism, cell structure, and chaperone, antioxidant, and proteolytic activity. We determined that the muscle HS response is both fiber type and time specific. Overall, more differences were observed in the red semitendinosus than in the white semitendinosus, although the time point at which differences were observed varied. These data show that as little as 2 h of HS has measurable effects on muscle proteins, indicating that acute HS has the potential to impair muscle function and growth.