Spontaneous and Voltage-Activated Elementary Calcium Release Events in Intact Skeletal Muscle Fibers Expressing the Embryonic CaV1.1 Splice Variant

The adult isoform of voltage-gated L-type calcium channel (CaV1.1a) opens slowly at strong depolarizations, its contribution to the calcium influx during an action potential is negligible in skeletal muscle. In contrast, calcium influx through the embryonic splice variant (CaV1.1e) substantially contributes to depolarization-induced calcium transients as this isoform displays an altered voltage-dependence and gating kinetics as compared to...