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dc.contributor.authorSteenbergen, Josef M.
dc.contributor.authorFay, Fredric S.
dc.date2022-08-11T08:10:04.000
dc.date.accessioned2022-08-23T16:54:14Z
dc.date.available2022-08-23T16:54:14Z
dc.date.issued1996-01-26
dc.date.submitted2008-08-15
dc.identifier.citation<p>J Biol Chem. 1996 Jan 26;271(4):1821-4.</p>
dc.identifier.issn0021-9258 (Print)
dc.identifier.doi10.1074/jbc.271.4.1821
dc.identifier.pmid8567621
dc.identifier.urihttp://hdl.handle.net/20.500.14038/42455
dc.description.abstractCalcium release from intracellular stores occurs in a graded manner in response to increasing concentrations of either inositol 1,4,5-trisphosphate or caffeine. To investigate the mechanism responsible for this quantal release phenomenon, [Ca2+] changes inside intracellular stores in isolated single smooth muscle cells were monitored with mag-fura 2. Following permeabilization with saponin or alpha-toxin the dye, loaded via its acetoxymethyl ester, was predominantly trapped in the sarcoplasmic reticulum (SR). Low caffeine concentrations in the absence of ATP induced only partial Ca2+ release; however, after inhibiting the calcium pump with thapsigargin the same stimulus released twice as much Ca2+. When the SR Ca(2+)-ATPase was rendered non-functional by depleting its "ATP pool," submaximal caffeine doses almost fully emptied the stores of Ca2+. We conclude that quantal release of Ca2+ in response to caffeine in these smooth muscle cells is largely due to the activity of the SR Ca(2+)-ATPase, which appears to return a portion of the released Ca2+ back to the SR, even in the absence of ATP. Apparently the SR Ca(2+)-ATPase is fueled by ATP, which is either compartmentalized or bound to the SR.
dc.language.isoen_US
dc.relation<p><a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=8567621&dopt=Abstract">Link to Article in PubMed</a></p>
dc.relation.urlhttps://doi.org/10.1074/jbc.271.4.1821
dc.subjectAdenosine Triphosphate
dc.subjectAnimals
dc.subjectBufo marinus
dc.subjectCaffeine
dc.subjectCalcium
dc.subjectCalcium Channels
dc.subjectCalcium-Transporting ATPases
dc.subjectCell Compartmentation
dc.subjectCell Membrane Permeability
dc.subjectCells, Cultured
dc.subjectDetergents
dc.subjectDose-Response Relationship, Drug
dc.subjectEnzyme Activation
dc.subjectEnzyme Inhibitors
dc.subjectIon Channel Gating
dc.subjectMuscle Proteins
dc.subjectMuscle, Smooth
dc.subjectRyanodine Receptor Calcium Release Channel
dc.subjectSaponins
dc.subjectSarcoplasmic Reticulum
dc.subjectTerpenes
dc.subjectThapsigargin
dc.subjectLife Sciences
dc.subjectMedicine and Health Sciences
dc.titleThe quantal nature of calcium release to caffeine in single smooth muscle cells results from activation of the sarcoplasmic reticulum Ca(2+)-ATPase
dc.typeArticle
dc.source.journaltitleThe Journal of biological chemistry
dc.source.volume271
dc.source.issue4
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/oapubs/802
dc.identifier.contextkey579687
html.description.abstract<p>Calcium release from intracellular stores occurs in a graded manner in response to increasing concentrations of either inositol 1,4,5-trisphosphate or caffeine. To investigate the mechanism responsible for this quantal release phenomenon, [Ca2+] changes inside intracellular stores in isolated single smooth muscle cells were monitored with mag-fura 2. Following permeabilization with saponin or alpha-toxin the dye, loaded via its acetoxymethyl ester, was predominantly trapped in the sarcoplasmic reticulum (SR). Low caffeine concentrations in the absence of ATP induced only partial Ca2+ release; however, after inhibiting the calcium pump with thapsigargin the same stimulus released twice as much Ca2+. When the SR Ca(2+)-ATPase was rendered non-functional by depleting its "ATP pool," submaximal caffeine doses almost fully emptied the stores of Ca2+. We conclude that quantal release of Ca2+ in response to caffeine in these smooth muscle cells is largely due to the activity of the SR Ca(2+)-ATPase, which appears to return a portion of the released Ca2+ back to the SR, even in the absence of ATP. Apparently the SR Ca(2+)-ATPase is fueled by ATP, which is either compartmentalized or bound to the SR.</p>
dc.identifier.submissionpathoapubs/802
dc.contributor.departmentDepartment of Physiology
dc.source.pages1821-4


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