title: Hypotonic medium increases calcium permeant channels activity in human normal and dystrophic myotubes.
abstract: Duchenne muscular dystrophy (DMD) is characterized by the absence of dystrophin and an elevated intracellular calcium level. Single-channel recordings were performed with the cell-attached configuration of the patch-clamp technique. The present study shows, on human co-cultured normal and dystrophic muscle cells, the evidence for an increased activity of calcium permeant cationic mechano-sensitive channels under hypotonic medium stimulation. This activity was particularly enhanced in DMD cells. The hypotonic medium induced drastic changes in the single-channel activity characteristics, which are: a large increase of the calcium over potassium permeability ratio; and a great enhancement of the quantity of current crossing through these channels. These channels could contribute to a significant calcium entry, which could participate in the abnormal calcium homeostasis observed in DMD muscle.
authors.affiliation: Laboratoire de Biomembranes et Signalisation Cellulaire, UMR CNRS/Université de Poitiers 6558, 86022 Poitiers Cedex, France. clarisse.vandebrouck@fymu.ucl.ac.be
authors.forename: Clarisse
authors.initials: C
authors.lastname: Vandebrouck
authors.forename: Gérard
authors.initials: G
authors.lastname: Duport
authors.forename: Guy
authors.initials: G
authors.lastname: Raymond
authors.forename: Christian
authors.initials: C
authors.lastname: Cognard
mesh_terms: D000293:Adolescent; D000328:Adult; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000187:drug effects / Q000378:metabolism; D002412:Cations / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D005682:Gadolinium / Q000494:pharmacology; D006801:Humans; D007038:Hypotonic Solutions / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D020388:Muscular Dystrophy, Duchenne / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology
chemical_list: D015220:Calcium Channels; D027682:Cation Transport Proteins; D002412:Cations; D007038:Hypotonic Solutions; D005682:Gadolinium; D002118:Calcium