Monocarboxylate transporter expression at the onset of skeletal muscle regeneration

Abstract

Monocarboxylate transporters (MCTs) are involved in lactate transport across the cell membrane and this has important implications for energetic efficiency of skeletal muscle. MCT expression is affected by mechanical overload, chronic electrical stimuli, and voluntary wheel running. However, the cellular regulation of MCT protein expression at the onset of skeletal muscle regeneration is unknown.PURPOSETo determine protein and gene expression of MCTs at the onset of skeletal muscle regeneration. Male C57/BL6 (12 weeks old) mice were randomly assigned to a control (uninjured) or bupivacaine (injured) group. Bupivacaine was injected into the tibialis anterior (TA) of the injured group and phosphate buffered saline (PBS) was injected into the TA of the uninjured group. The TA was extracted 3 days post‐bupivacaine injection. A 12% decrease in TA muscle mass to tibia length (2.43 ± 0.12 mg/mm vs. 2.14 ± 0.19 mg/mm, p < 0.02) was observed. IGF‐1 and myoD gene expression increased 5.0‐fold (p < 0.05) and 3.5‐fold (p < 0.05), respectively during regeneration. MCT1 protein decreased 32% (p < 0.03); however, gene expression was not altered. There was no difference in MCT4 protein or gene expression. CD147 and PKCθ protein increased 64% (p < 0.03) and 79% (p < 0.02), respectively. In conclusion, at the onset of skeletal muscle regeneration MCT1 protein is decreased and this appears to be regulated post‐transcriptionally.