Cationic channels in normal and dystrophic human myotubes

Human skeletal muscle cells obtained from normal and Duchenne muscular dyst rophy patients were cocultured with explants of rat dorsal root ganglions. Single-channel recordings were performed with the cell-attached configurati on of the patch-clamp technique and negative pressure was applied via the p atch-pipette in order to mechanically stimulate the membrane patch. Inward elementary current activity was recorded under control or negative pressure conditions. Its occurrence and mean open probability were higher in Duchen ne muscular dystrophy. Amplitude histograms reveal that these channels have a: small unitary conductance of around 10 pS in 110 mM Ca2+ and could be i nhibited in a dose-dependent manner by gadolinium. Results show that the me mbrane stress favoured calcium permeation through these channels. Taken tog ether these data provide arguments for the involvement of such channels in calcium overload previously observed in cocultured dystrophic human (Duchen ne muscular dystrophy) muscle cells. (C) 2000 Elsevier Science B.V. All rig hts reserved.