Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2005-3-1
pubmed:abstractText
The L-type Ca(2+) channels Ca(V)1.1 (alpha(1S)) and Ca(V)1.2 (alpha(1C)) share properties of targeting but differ by their mode of coupling to ryanodine receptors in muscle cells. The brain isoform Ca(V)2.1 (alpha(1A)) lacks ryanodine receptor targeting. We studied these three isoforms in myotubes of the alpha(1S)-deficient skeletal muscle cell line GLT under voltage-clamp conditions and estimated the flux of Ca(2+) (Ca(2+) input flux) resulting from Ca(2+) entry and release. Surprisingly, amplitude and kinetics of the input flux were similar for alpha(1C) and alpha(1A) despite a previously reported strong difference in responsiveness to extracellular stimulation. The kinetic flux characteristics of alpha(1C) and alpha(1A) resembled those in alpha(1S)-expressing cells but the contribution of Ca(2+) entry was much larger. alpha(1C) but not alpha(1A)-expressing cells revealed a distinct transient flux component sensitive to sarcoplasmic reticulum depletion by 30 microM cyclopiazonic acid and 10 mM caffeine. This component likely results from synchronized Ca(2+)-induced Ca(2+) release that is absent in alpha(1A)-expressing myotubes. In cells expressing an alpha(1A)-derivative (alpha(1)Aas(1592-clip)) containing the putative targeting sequence of alpha(1S), a similar transient component was noticeable. Yet, it was considerably smaller than in alpha(1C), indicating that the local Ca(2+) entry produced by the chimera is less effective in triggering Ca(2+) release despite similar global Ca(2+) inward current density.
pubmed:commentsCorrections
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pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0006-3495
pubmed:author
pubmed:issnType
Print
pubmed:volume
88
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1765-77
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Functional interaction of CaV channel isoforms with ryanodine receptors studied in dysgenic myotubes.
pubmed:affiliation
Department of Applied Physiology, University of Ulm, Albert-Einstein-Allee 11, D-89069 Ulm, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't