Modulation of the voltage sensor of L-type Ca2+ channels by intracellular Ca2+.

ABSTRACT: Both intracellular calcium and transmembrane voltage cause inactivation, or spontaneous closure, of L-type (CaV1.2) calcium channels. Here we show that long-lasting elevations of intracellular calcium to the concentrations that are expected to be near an open channel (>/=100 microM) completely and reversibly blocked calcium current through L-type channels. Although charge movements associated with the opening (ON) motion of the channel's voltage sensor were not altered by high calcium, the closing (OFF) transition was impeded. In two-pulse experiments, the blockade of calcium current and the reduction of gating charge movements available for the second pulse developed in parallel during calcium load. The effect depended steeply on voltage and occurred only after a third of the total gating

SUBMITTER: Isaev D 

PROVIDER: S-EPMC2234499 | biostudies-literature | 2004 May

REPOSITORIES: biostudies-literature