Hypotonic medium increases calcium permeant channels activity in human normal and dystrophic myotubes.
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.
Vandebrouck
Clarisse
C
Laboratoire de Biomembranes et Signalisation Cellulaire, UMR CNRS/Université de Poitiers 6558, 86022 Poitiers Cedex, France. clarisse.vandebrouck@fymu.ucl.ac.be
Duport
Gérard
G
Raymond
Guy
G
Cognard
Christian
C
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
D015220:Calcium Channels; D027682:Cation Transport Proteins; D002412:Cations; D007038:Hypotonic Solutions; D005682:Gadolinium; D002118:Calcium