%0 Journal Article %T Voltage-activated elementary calcium release events in isolated mouse skeletal muscle fibers. %+ Department of Physiology %+ Physiologie intégrative, cellulaire et moléculaire (PICM) %+ Grenoble Institut des Neurosciences (GIN) %A Csernoch, Laszlo %A Pouvreau, Sandrine %A Ronjat, Michel %A Jacquemond, Vincent %Z CNRS; University Claude Bernard Lyon 1; Association Française contre les Myopathies; the Hungarian National Science Fund (OTKA T049151); French-Hungarian Balaton program %< avec comité de lecture %@ 0022-2631 %J Journal of Membrane Biology %I Springer Verlag (Germany) %V 226 %N 1-3 %P 43-55 %8 2008-11 %D 2008 %R 10.1007/s00232-008-9138-0 %M 19015802 %Z Life Sciences [q-bio]/Cellular BiologyJournal articles %X The elementary Ca(2+)-release events underlying voltage-activated myoplasmic Ca(2+) transients in mammalian muscle remain elusive. Here, we looked for such events in confocal line-scan (x,t) images of fluo-3 fluorescence taken from isolated adult mouse skeletal muscle fibers held under voltage-clamp conditions. In response to step depolarizations, spatially segregated fluorescence signals could be detected that were riding on a global increase in fluorescence. These discrete signals were separated using digital filtering in the spatial domain; mean values for their spatial half-width and amplitude were 1.99 +/- 0.09 microm and 0.16 +/- 0.005 DeltaF/F(0) (n = 151), respectively. Under control conditions, the duration of the events was limited by the pulse duration. In contrast, in the presence of maurocalcine, a scorpion toxin suspected to disrupt the process of repolarization-induced ryanodine receptor (RyR) closure, events uninterrupted by the end of the pulse were readily detected. Overall results establish these voltage-activated low-amplitude local Ca(2+) signals as inherent components of the physiological Ca(2+)-release process of mammalian muscle and suggest that they result from the opening of either one RyR or a coherently operating group of RyRs, under the control of the plasma membrane polarization. %G English %2 https://inserm.hal.science/inserm-00401126/document %2 https://inserm.hal.science/inserm-00401126/file/inserm-00401126_edited.pdf %2 https://inserm.hal.science/inserm-00401126/file/Voltage_activated.pdf %L inserm-00401126 %U https://inserm.hal.science/inserm-00401126 %~ INSERM %~ UGA %~ CNRS %~ UNIV-GRENOBLE1 %~ UNIV-LYON1 %~ U836 %~ UDL %~ UNIV-LYON