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dc.contributor.authorWiden, Ceciliaen_US
dc.contributor.authorBarclay, Chrisen_US
dc.date.accessioned2017-04-24T08:34:38Z
dc.date.available2017-04-24T08:34:38Z
dc.date.issued2006en_US
dc.date.modified2008-11-10T07:10:32Z
dc.identifier.issn00223751en_US
dc.identifier.doi10.1113/jphysiol.2006.104992en_AU
dc.identifier.urihttp://hdl.handle.net/10072/14253
dc.description.abstractThe aim of this study was to quantify the fraction of cross-bridges that cycle during a cardiac twitch. Measurements of the energetics of contracting left ventricular mouse papillary muscle were made in vitro (27C) using the myothermic technique. Enthalpy output was partitioned into force-dependent and force-independent components using 2,3-butanedione monoxime (BDM) to selectively inhibit cross-bridge cycling. For isometric contractions and a contraction frequency of 2 Hz the net enthalpy output was 5.7 ᰮ8 mJ/g/twitch and initial enthalpy output was 2.3 ᰮ3 mJ/g/twitch (n =11). Assuming that low concentrations of BDM did not affect Ca2+ cycling, force-independent enthalpy output was 18.6 ᱮ9% (n =7) of the initial enthalpy output. Enthalpy output decreased with increased contraction frequency but was independent of shortening velocity. On the basis of these values, it was calculated that the twitch energetics were consistent with ATP splitting by half the cross-bridges and the pumping of one Ca2+ into the sarcoplasmic reticulum for every three cross-bridge cycles. The simplest interpretation is that half the cross-bridges completed one ATP-splitting cycle in each twitch. The lack of influence of shortening velocity on energy cost supports the idea that the amount of energy to be used is determined early in a twitch and is not greatly influenced by events that occur during the contraction.en_US
dc.description.peerreviewedYesen_US
dc.description.publicationstatusYesen_AU
dc.languageEnglishen_US
dc.language.isoen_AU
dc.publisherBlackwell Publishing Ltden_US
dc.publisher.placeOxford, UKen_US
dc.publisher.urihttp://www.blackwellpublishing.com/journal.asp?ref=0022-3751&site=1en_AU
dc.relation.ispartofstudentpublicationYen_AU
dc.relation.ispartofpagefrom5en_US
dc.relation.ispartofpageto15en_US
dc.relation.ispartofissue1en_US
dc.relation.ispartofjournalThe Journal of Physiologyen_US
dc.relation.ispartofvolume573en_US
dc.rights.retentionNen_AU
dc.subject.fieldofresearchcode270602en_US
dc.titleATP splitting by half the cross-bridges can explain the twitch energetics of mouse papillary muscleen_US
dc.typeJournal articleen_US
dc.type.descriptionC1 - Peer Reviewed (HERDC)en_US
dc.type.codeC - Journal Articlesen_US
gro.facultyGriffith Health, School of Allied Health Sciencesen_US
gro.date.issued2006
gro.hasfulltextNo Full Text


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