Key result
The CaV 1.2 calcium channel is expressed in the sarcolemma of type I and IIa myofibers of adult skeletal muscle, and exercise increases the number of both CaV 1.2 and type IIa-positive fibers.
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.
Hypothesis-generating in animal models; leaves open CaV1.2 modulation for human muscle phenotype maintenance.
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.
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Jeftinija et al. (2007) studied Adult skeletal muscle. Exercise-induced alterations was evaluated on Expression of CaV 1.1 and CaV 1.2 channels. The CaV 1.2 calcium channel is expressed in the sarcolemma of type I and IIa myofibers of adult skeletal muscle, and exercise increases the number of both CaV 1.2 and type IIa-positive fibers.
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