We are also interested in the CLC-1 channel because it plays an important role in membrane repolarization of skeletal muscle cells following muscular contraction, and its mutation in humans causes hereditary muscle disorders known as myotonia congenita (George et al., 1993; Koch et al., 1992; Lorenz et al., 1994; Steinmeyer et al., 1991). This evidence concerns the gene CLCN1 and Thomsen and Becker disease.