Effects of pH on membrane resistance in normal and dystrophic mouse skeletal muscle fibers

Abstract

Membrane cable properties of skeletal muscle fibers of dystrophic mice (Rej-129) and their littermate controls were examined using a conventional two-microelectrode recording technique. Fibers from dystrophic mice had a decreased membrane resistivity ( R m) compared with those from normal mice (517 ± 27 vs 642 ± 34 Ω − cm 2), while the internal resistivities ( R i) did not differ significantly. The increase in membrane specific conductance was due to an increased Cl − conductance ( g Cl) (2304 vs 1346 μS/cm 2 for normal fibers), although the K + conductance ( g K) was actually decreased (234 vs 369 μS/cm 2 for normal fibers). With changes in pH, membrane conductances of normal and dystrophic skeletal muscle fibers varied differently, mainly due to differences in effects on the Cl − conductance. This contrast may be due to altered regulation of internal pH in dystrophic muscle.