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dc.contributor.authorZhuge, Ronghua
dc.contributor.authorFogarty, Kevin E.
dc.contributor.authorBaker, Stephen P.
dc.contributor.authorMcCarron, John G.
dc.contributor.authorTuft, Richard A.
dc.contributor.authorLifshitz, Lawrence M.
dc.contributor.authorWalsh, John V. Jr.
dc.date2022-08-11T08:09:31.000
dc.date.accessioned2022-08-23T16:33:57Z
dc.date.available2022-08-23T16:33:57Z
dc.date.issued2004-08-13
dc.date.submitted2007-12-21
dc.identifier.citationAm J Physiol Cell Physiol. 2004 Dec;287(6):C1577-88. Epub 2004 Aug 11. <a href="http://dx.doi.org/10.1152/ajpcell.00153.2004">Link to article on publisher's site</a>
dc.identifier.issn0363-6143 (Print)
dc.identifier.doi10.1152/ajpcell.00153.2004
dc.identifier.pmid15306542
dc.identifier.urihttp://hdl.handle.net/20.500.14038/38223
dc.description.abstractCa(2+) sparks are highly localized Ca(2+) transients caused by Ca(2+) release from sarcoplasmic reticulum through ryanodine receptors (RyR). In smooth muscle, Ca(2+) sparks activate nearby large-conductance, Ca(2+)-sensitive K(+) (BK) channels to generate spontaneous transient outward currents (STOC). The properties of individual sites that give rise to Ca(2+) sparks have not been examined systematically. We have characterized individual sites in amphibian gastric smooth muscle cells with simultaneous high-speed imaging of Ca(2+) sparks using wide-field digital microscopy and patch-clamp recording of STOC in whole cell mode. We used a signal mass approach to measure the total Ca(2+) released at a site and to estimate the Ca(2+) current flowing through RyR [I(Ca(spark))]. The variance between spark sites was significantly greater than the intrasite variance for the following parameters: Ca(2+) signal mass, I(Ca(spark)), STOC amplitude, and 5-ms isochronic STOC amplitude. Sites that failed to generate STOC did so consistently, while those at the remaining sites generated STOC without failure, allowing the sites to be divided into STOC-generating and STOC-less sites. We also determined the average number of spark sites, which was 42/cell at a minimum and more likely on the order of at least 400/cell. We conclude that 1) spark sites differ in the number of RyR, BK channels, and coupling ratio of RyR-BK channels, and 2) there are numerous Ca(2+) spark-generating sites in smooth muscle cells. The implications of these findings for the organization of the spark microdomain are explored.
dc.language.isoen_US
dc.relation<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15306542&dopt=Abstract ">Link to article in PubMed</a>
dc.relation.urlhttp://dx.doi.org/10.1152/ajpcell.00153.2004
dc.subjectAnimals
dc.subjectBufo marinus
dc.subjectCalcium
dc.subjectCalcium Signaling
dc.subjectCytoplasm
dc.subjectLarge-Conductance Calcium-Activated Potassium Channels
dc.subjectMicroscopy, Fluorescence
dc.subjectMyocytes, Smooth Muscle
dc.subjectPatch-Clamp Techniques
dc.subjectPotassium Channels, Calcium-Activated
dc.subjectRyanodine Receptor Calcium Release Channel
dc.subjectSarcoplasmic Reticulum
dc.subjectLife Sciences
dc.subjectMedicine and Health Sciences
dc.titleCa(2+) spark sites in smooth muscle cells are numerous and differ in number of ryanodine receptors, large-conductance K(+) channels, and coupling ratio between them
dc.typeJournal Article
dc.source.journaltitleAmerican journal of physiology. Cell physiology
dc.source.volume287
dc.source.issue6
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/oapubs/110
dc.identifier.contextkey407405
html.description.abstract<p>Ca(2+) sparks are highly localized Ca(2+) transients caused by Ca(2+) release from sarcoplasmic reticulum through ryanodine receptors (RyR). In smooth muscle, Ca(2+) sparks activate nearby large-conductance, Ca(2+)-sensitive K(+) (BK) channels to generate spontaneous transient outward currents (STOC). The properties of individual sites that give rise to Ca(2+) sparks have not been examined systematically. We have characterized individual sites in amphibian gastric smooth muscle cells with simultaneous high-speed imaging of Ca(2+) sparks using wide-field digital microscopy and patch-clamp recording of STOC in whole cell mode. We used a signal mass approach to measure the total Ca(2+) released at a site and to estimate the Ca(2+) current flowing through RyR [I(Ca(spark))]. The variance between spark sites was significantly greater than the intrasite variance for the following parameters: Ca(2+) signal mass, I(Ca(spark)), STOC amplitude, and 5-ms isochronic STOC amplitude. Sites that failed to generate STOC did so consistently, while those at the remaining sites generated STOC without failure, allowing the sites to be divided into STOC-generating and STOC-less sites. We also determined the average number of spark sites, which was 42/cell at a minimum and more likely on the order of at least 400/cell. We conclude that 1) spark sites differ in the number of RyR, BK channels, and coupling ratio of RyR-BK channels, and 2) there are numerous Ca(2+) spark-generating sites in smooth muscle cells. The implications of these findings for the organization of the spark microdomain are explored.</p>
dc.identifier.submissionpathoapubs/110
dc.contributor.departmentDepartment of Cell Biology
dc.contributor.departmentGraduate School of Biomedical Sciences
dc.contributor.departmentDepartment of Physiology
dc.source.pagesC1577-88


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