Dataset Information

Calcium-induced calcium release in smooth muscle: loose coupling between the action potential and calcium release.

ABSTRACT: Calcium-induced calcium release (CICR) has been observed in cardiac myocytes as elementary calcium release events (calcium sparks) associated with the opening of L-type Ca(2+) channels. In heart cells, a tight coupling between the gating of single L-type Ca(2+) channels and ryanodine receptors (RYRs) underlies calcium release. Here we demonstrate that L-type Ca(2+) channels activate RYRs to produce CICR in smooth muscle cells in the form of Ca(2+) sparks and propagated Ca(2+) waves. However, unlike CICR in cardiac muscle, RYR channel opening is not tightly linked to the gating of L-type Ca(2+) channels. L-type Ca(2+) channels can open without triggering Ca(2+) sparks and triggered Ca(2+) sparks are often observed after channel closure. CICR is a function of the net flux of Ca(2+) ions into the cytosol, rather than the single channel amplitude of L-type Ca(2+) channels. Moreover, unlike CICR in striated muscle, calcium release is completely eliminated by cytosolic calcium buffering. Thus, L-type Ca(2+) channels are loosely coupled to RYR through an increase in global [Ca(2+)] due to an increase in the effective distance between L-type Ca(2+) channels and RYR, resulting in an uncoupling of the obligate relationship that exists in striated muscle between the action potential and calcium release.

SUBMITTER: Collier ML

PROVIDER: S-EPMC2217224 | biostudies-literature | 2000 May

REPOSITORIES: biostudies-literature

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Calcium-induced calcium release in smooth muscle: loose coupling between the action potential and calcium release.

Collier M L ML Ji G G Wang Y Y Kotlikoff M I MI

The Journal of general physiology 20000501 5

Calcium-induced calcium release (CICR) has been observed in cardiac myocytes as elementary calcium release events (calcium sparks) associated with the opening of L-type Ca(2+) channels. In heart cells, a tight coupling between the gating of single L-type Ca(2+) channels and ryanodine receptors (RYRs) underlies calcium release. Here we demonstrate that L-type Ca(2+) channels activate RYRs to produce CICR in smooth muscle cells in the form of Ca(2+) sparks and propagated Ca(2+) waves. However, unl ...[more]

PMID: 10779321

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Dataset Information

Calcium-induced calcium release in smooth muscle: loose coupling between the action potential and calcium release.

Publications

Calcium-induced calcium release in smooth muscle: loose coupling between the action potential and calcium release.

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