The effect of taurine and β-alanine supplementation on taurine transporter protein and fatigue resistance in skeletal muscle from mdx mice

This study investigated the effect of taurine and β-alanine supplementation on muscle function and muscle taurine transporter (TauT) protein expression in mdx mice. Wild-type (WT) and mdx mice (5 months) were supplemented with taurine or β-alanine for 4 weeks, after which in vitro contractile properties, fatigue resistance and force recovery, and the expression of the TauT protein and proteins involved in excitation-contraction (E-C) coupling were examined in fast-twitch muscle. There was no difference in basal TauT protein expression or basal taurine content between mdx than WT muscle. Supplementation with taurine and β-alanine increased and reduced taurine content, respectively, in muscle from WT and mdx mice but had no effect of TauT protein. Taurine supplementation reduced body and muscle mass, and enhanced fatigue resistance and force recovery in mdx muscle. β-Alanine supplementation enhanced fatigue resistance in WT and mdx muscle. There was no difference in the basal expression of key E-C coupling proteins [ryanodine receptor 1 (RyR1), dihydropyridine receptor (DHPR), sarco(endo)plasmic reticulum Ca²⁺-ATPase 1 (SERCA1) or calsequestrin 1 (CSQ1)] between WT and mdx mice, and the expression of these proteins was not altered by taurine or β-alanine supplementation. These findings suggest that TauT protein expression is relatively insensitive to changes in muscle taurine content in WT and mdx mice, and that taurine and β-alanine supplementation may be viable therapeutic strategies to improve fatigue resistance of dystrophic skeletal muscle.