Cationic channels in normal and dystrophic human myotubes.
Human skeletal muscle cells obtained from normal and Duchenne muscular dystrophy patients were cocultured with explants of rat dorsal root ganglions. Single-channel recordings were performed with the cell-attached configuration of the patch-clamp technique and negative pressure was applied via the patch-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 Duchenne muscular dystrophy. Amplitude histograms reveal that these channels have a small unitary conductance of around 10 pS in 110 mM Ca2+ and could be inhibited in a dose-dependent manner by gadolinium. Results show that the membrane stress favoured calcium permeation through these channels. Taken together these data provide arguments for the involvement of such channels in calcium overload previously observed in cocultured dystrophic human (Duchenne muscular dystrophy) muscle cells.
Vandebrouck
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Laboratoire de Biomembranes et Signalisation Cellulaire, UMR CNRS/Université de Poitiers 6558, 40 Avenue du Recteur Pineau, F-86022 Poitiers, Cedex, France. phygen@campus.univ-poitiers.fr
Duport
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Cognard
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Raymond
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D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology; D002412:Cations / Q000378:metabolism* / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured / Q000378:metabolism / Q000473:pathology; D018920:Coculture Techniques; D006801:Humans; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D008564:Membrane Potentials / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000378:metabolism* / Q000473:pathology; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D020388:Muscular Dystrophy, Duchenne / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D051381:Rats; D013314:Stress, Mechanical
D002412:Cations; D007473:Ion Channels; D002118:Calcium