Arginine promotes myogenic differentiation and myotube formation through the elevation of cytoplasmic calcium concentration

This study aimed to explore the mechanism underlying arginine-promoted myogenesis of myoblasts.C2C12 cells were cultured with a medium containing 0.1,0.4,0.8,or 1.2 mmol/L arginine,respectively.Cell proliferation,viability,differentiation indexes,cytoplasmic Ca^(2+)concentration,and relative mRNA expression levels of myogenic regulatory factors(MRF)and key Ca2+channels were measured in the absence or presence of 2 chemical inhibitors,dantrolene(DAN,10μmol/L)and nisoldipine(NIS,10μmol/L),respectively.Results demonstrated that arginine promoted myogenic differentiation and myotube formation.Compared with the control(0.4 mmol/L arginine),1.2 mmol/L arginine upregulated the relative mRNA expression levels of myogenin(MyoG)and Myomaker at d 2 during myogenic induction(P<0.05).Cytoplasmic Ca^(2+)concentrations were significantly elevated by arginine supplementation at d 2 and 4(P<0.05).Relative mRNA expression levels of Ca^(2+)channels including the type 1 ryanodine recepto r(RyR1)and voltage-gated Ca^(2+)channel(Cav1.1)were upregulated by 1.2 mmol/L arginine during2-d myogenic induction(P<0.01).However,arginine-promoted myogenic potential of myoblasts was remarkably compromised by DAN and NIS,respectively(P<0.05).These findings evidenced that the supplementation of arginine promoted myogenic differentiation and myotube formation through increasing cytoplasmic Ca^(2+)concentration from both extracellular and sarcoplasmic reticulum Ca^(2+).