Cardiac activation heat remains inversely dependent on temperature over the range 27-37°C

Show simple item record Johnston, CM en Han, June en Loiselle, Denis en Nielsen, Poul en Taberner, Andrew en 2016-07-12T01:33:35Z en 2016-06-01 en
dc.identifier.citation American Journal of Physiology - Heart and Circulatory Physiology, 2016, 310 (11), pp. H1512 - H1519 en
dc.identifier.issn 0363-6135 en
dc.identifier.uri en
dc.description.abstract The relation between heat output and stress production (force per cross-sectional area) of isolated cardiac tissue is a key metric that provides insight into muscle energetic performance. The heat intercept of the relation, termed "activation heat," reflects the metabolic cost of restoring transmembrane gradients of Na(+) and K(+) following electrical excitation, and myoplasmic Ca(2+) concentration following its release from the sarcoplasmic reticulum. At subphysiological temperatures, activation heat is inversely dependent on temperature. Thus one may presume that activation heat would decrease even further at body temperature. However, this assumption is prima facie inconsistent with a study, using intact hearts, which revealed no apparent change in the combination of activation and basal metabolism between 27 and 37°C. It is thus desired to directly determine the change in activation heat between 27 and 37°C. In this study, we use our recently constructed high-thermal resolution muscle calorimeter to determine the first heat-stress relation of isolated cardiac muscle at 37°C. We compare the relation at 37°C to that at 27°C to examine whether the inverse temperature dependence of activation heat, observed under hypothermic conditions, prevails at body temperature. Our results show that activation heat was reduced (from 3.5 ± 0.3 to 2.3 ± 0.3 kJ/m(3)) at the higher temperature. This leads us to conclude that activation metabolism continues to decline as temperature is increased from hypothermia to normothermia and allows us to comment on results obtained from the intact heart by previous investigators. en
dc.description.uri en
dc.publisher American Physiological Society en
dc.relation.ispartofseries American Journal of Physiology - Heart and Circulatory Physiology en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. Details obtained from en
dc.rights.uri en
dc.title Cardiac activation heat remains inversely dependent on temperature over the range 27-37°C en
dc.type Journal Article en
dc.identifier.doi 10.1152/ajpheart.00903.2015 en
pubs.issue 11 en
pubs.begin-page H1512 en
pubs.volume 310 en
dc.description.version AM - Accepted Manuscript en
dc.rights.holder Copyright: American Physiological Society en
dc.identifier.pmid 27016583 en en
pubs.end-page H1519 en
pubs.publication-status Published en
dc.rights.accessrights en
pubs.subtype Article en
pubs.elements-id 525643 en Bioengineering Institute en ABI Associates en Engineering en Engineering Science en Science en Science Research en Maurice Wilkins Centre (2010-2014) en
dc.identifier.eissn 1522-1539 en
pubs.record-created-at-source-date 2016-07-12 en
pubs.dimensions-id 27016583 en

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