title: The Ca(V) 1.2 Ca(2+) channel is expressed in sarcolemma of type I and IIa myofibers of adult skeletal muscle.
abstract: Although Ca(2+)-dependent signaling pathways are important for skeletal muscle plasticity, the sources of Ca(2+) that activate these signaling pathways are not completely understood. Influx of Ca(2+) through surface membrane Ca(2+) channels may activate these pathways. We examined expression of two L-type Ca(2+) channels in adult skeletal muscle, the Ca(V) 1.1 and Ca(V) 1.2, with isoform-specific antibodies in Western blots and immunocytochemistry assays. Consistent with a large body of work, expression of the Ca(V) 1.1 was restricted to skeletal muscle where it was expressed in T-tubules. Ca(V) 1.2 was also expressed in skeletal muscle, in the sarcolemma of type I and IIa myofibers. Exercise-induced alterations in muscle fiber types cause a concomitant increase in the number of both Ca(V) 1.2 and type IIa-positive fibers. Taken together, these data suggest that the Ca(V) 1.2 Ca(2+) channel is expressed in adult skeletal muscle in a fiber type-specific manner, which may help to maintain oxidative muscle phenotype.
authors.affiliation: Department of Molecular and Biomedical Pharmacology, University of Kentucky Medical Center, Lexington, KY 40536, USA.
authors.forename: Dusan M
authors.initials: DM
authors.lastname: Jeftinija
authors.forename: Qing Bo
authors.initials: QB
authors.lastname: Wang
authors.forename: Sadie L
authors.initials: SL
authors.lastname: Hebert
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Norris
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yan
authors.forename: Mark M
authors.initials: MM
authors.lastname: Rich
authors.forename: Susan D
authors.initials: SD
authors.lastname: Kraner
mesh_terms: D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D051244:Caveolin 3 / Q000378:metabolism; D016189:Dystrophin / Q000378:metabolism; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism / Q000648:ultrastructure*; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism / Q000648:ultrastructure*; D018482:Muscle, Skeletal / Q000166:cytology*; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D012508:Sarcolemma / Q000378:metabolism*
chemical_list: D020746:Calcium Channels, L-Type; D051244:Caveolin 3; D016189:Dystrophin; C419385:L-type calcium channel alpha(1C); D020033:Protein Isoforms