K+cycling in the cochlea is critical to maintain hearing.Many sodium-potassium pumps are proved to participate in K+cycling,such as Na/K-ATPase.The α2-Na/K-ATPase is an important isoform of Na/K-ATPase.The expression of α2-Na/K-ATPase in the cochlea is not clear.In this study,we used C57BL/6 mice as a model of presbycusis and implemented immunohistochemistry staining and quantitative real time-PCR,and the α2-Na/K-ATPase expression pattern was confirmed in the inner ear.It was found α2-Na/K-ATPase was expressed widely in cochlea and its mRNA and protein expression was gradually reduced with aging(4-,14-,26-and 48-weeks old mice).We suspected that,the down-regulation of α2-Na/K-ATPase expression might be associated with the remodeling of K+cycling,degeneration of morphological structure and decrease of hearing function in aging C57 mice.In conclusion,we speculated that the reduction of α2-Na/K-ATPase might play an important role in the pathogenesis of age-related hearing loss.