Inhibition of potassium chloride cotransporters impairs muscle contraction and induces atrophy in C2C12 myotubes

In skeletal muscle cells, the resting membrane potential is primarily determined by Cl-, necessitating precise regulation of intracellular and extracellular Cl- balance. Potassium chloride cotransporters (KCCs), members of the cation-chloride cotransporter superfamily, facilitate the efflux of K+ and Cl- at a 1:1 ratio. However, the specific roles of KCCs in skeletal muscle remain poorly understood. In this study, we investigated the function of KCCs in skeletal muscle cells using [(dihydroindenyl)oxy]acetic acid (DIOA), a KCCs inhibitor. DIOA treatment of cultured C2C12 myotubes impaired contractility in response to electrical pulse stimulation. Additionally, DIOA-treated myotubes exhibited muscle atrophy, accompanied by increased expression of atrogenes such as Atrogin-1 and MuRF1. These findings reveal a novel role for KCCs in skeletal muscle and provide insights that may contribute to the development of preventive or therapeutic strategies for muscle disorders and atrophy.