Abundance of ClC-1 chloride channel in human skeletal muscle: fiber type specific differences and effect of training

Abstract

Cl channel protein 1 (ClC-1) may be important for excitability and contractility in skeletal muscle, but ClC-1 abundance has not been examined in human muscle. The aim of the present study was to examine ClC-1 abundance in human skeletal muscle, including fiber type specific differences and the effect of exercise training. A commercially available antibody was tested with positive and negative control tissue, and it recognized specifically ClC-1 in the range from 100 to 150 kDa. Abundance of ClC-1 was 38% higher ( P < 0.01) in fast twitch Type IIa muscle fibers than in slow twitch Type I. Muscle ClC-1 abundance did not change with 4 wk of training consisting of 30 min cycling at 85% of maximal heart rate (HR) and 3 × 30-s all out sprints or during a 7-wk training period with 10-12 × 30 s uphill cycling and 4-5 × ~4 min cycling at 90%-95% of HR. ClC-1 abundance correlated negatively ( P < 0.01) with maximal oxygen consumption ( r = -0.552) and incremental exercise performance ( r = -0.546). In addition, trained cyclists had lower ( P < 0.01) ClC-1 abundance than lesser trained individuals. The present observations indicate that a low abundance of muscle ClC-1 may be beneficial for exercise performance, but the role of abundance and regulation of ClC-1 in skeletal muscle of humans with respect to exercise performance and trainability need to be elucidated. NEW & NOTEWORTHY Abundance of the Cl channel protein 1 (ClC-1) chloride channel may be important for excitability and contractility in human skeletal muscle and may therefore have implications for fatigue development. In this study, we confirmed ClC-1 specificity for a commercially available antibody, and this study is first to our knowledge to determine ClC-1 protein abundance in human muscle by Western blotting. We observed that abundance of ClC-1 was higher in fast compared with slow twitch fibers and lower in trained individuals than in recreationally active.

High‐intensity exercise training ameliorates aberrant expression of markers of mitochondrial turnover but not oxidative damage in skeletal muscle of men with essential hypertension

“…Samples from each subject were loaded on the same gel, with the samples from before training (Pre) being placed adjacent to the samples after training (Post). The same pool of a mixed human muscle standard lysate was loaded in three different wells per gel and the average intensity of these samples was used for normalization to allow gel‐to‐gel comparison, as previously described . Proteins were separated according to their molecular weight by SDS page gel electrophoresis and semi‐dry transferred to a PVDF membrane (Merck Millipore, Darmstadt, Germany).…”

Changes in Expression and Cellular Localization of Rat Skeletal Muscle ClC-1 Chloride Channel in Relation to Age, Myofiber Phenotype and PKC Modulation

“…Indeed fast-twitch muscles as EDL are characterized by a higher gCl and ClC-1 mRNA with respect to the slow-twitch SOL muscle (Pierno et al, 2002). In accordance with the greater presence of ClC-1 channels in fasttwitch muscles compared to slow-twitch muscles, recent evidence demonstrates that ClC-1 protein expression is higher in type IIa (fast-oxidative) fibers compared to type I (slowoxidative) fibers (Thomassen et al, 2018). The importance of ClC-1 in determining muscle phenotype is also evident during muscle disuse, due to bed rest or microgravity, when phenotype myofiber transition from slow to fast was observed in parallel with the early modification of gCl and ClC-1 channel expression (Pierno et al, 2002).…”

Beta2‐adrenergic agonist clenbuterol increases energy expenditure and fat oxidation, and induces mTOR phosphorylation in skeletal muscle of young healthy men

“…The protein‐specific content was determined by Western blotting as described previously . Briefly, freeze‐dried muscle tissue (~2 mg dw) was homogenized for 1 min at 30 Hz on a shaking bead‐mill (TissueLyser II, QIagen, Valencia, CA, USA) in ice‐cold lysis buffer (0.05 mol/L Tris Base pH 7.4, 0.15 mol/L NaCl, 1 mmol/L EDTA and EGTA, 0.05 mol/L sodium fluoride, 5 mmol/L sodium pyrophosphate, 2 mmol/L sodium orthovanadate, 1 mmol/L benzamidine, 0.5% protease inhibitor cocktail (P8340, Sigma Aldrich), and 1% NP‐40).…”