dc.contributor.author |
Han, June |
en |
dc.contributor.author |
Taberner, Andrew |
en |
dc.contributor.author |
Nielsen, Poul |
en |
dc.contributor.author |
Kirton, Robert |
en |
dc.contributor.author |
Ward, Marie-Louise |
en |
dc.contributor.author |
Loiselle, Denis |
en |
dc.date.accessioned |
2011-09-06T03:16:10Z |
en |
dc.date.issued |
2010 |
en |
dc.identifier.citation |
Am J Physiol Heart Circ Physiol 299(5):H1382-H1394 Nov 2010 |
en |
dc.identifier.uri |
http://hdl.handle.net/2292/7780 |
en |
dc.description.abstract |
The heat liberated upon stress production in isolated cardiac muscle provides insights into the complex thermodynamic processes underlying mechanical contraction. To that end, we simultaneously measured the heat and stress (force per cross-sectional area) production of cardiac trabeculae from rats using a flow-through micromechanocalorimeter. In a flowing stream of O2-equilibrated Tyrode solution (∼22°C), the stress and heat production of actively contracting trabeculae were varied by 1) altering stimulus frequency (0.2–4 Hz) at optimal muscle length (Lo), 2) reducing muscle length below Lo at 0.2 and 2 Hz, and 3) changing extracellular Ca2+ concentrations ([Ca2+]o; 1 and 2 mM). Linear regression lines were adequate to fit the active heat-stress data. The active heat-stress relationships were independent of stimulus frequency and muscle length but were dependent on [Ca2+]o, having greater intercepts at 2 mM [Ca2+]o than at 1 mM [Ca2+]o (3.5 and 2.0 kJ·m−3·twitch−1, respectively). The slopes among the heat-stress relationships did not differ. At the highest experimental stimulus frequency, pronounced elevation of diastolic Ca2+ resulted in incomplete twitch relaxation. The resulting increase of diastolic stress, which occurred with negligible metabolic energy expenditure, subsequently diminished due to the time-dependent loss of myofilament Ca2+-sensitivity. |
en |
dc.format.medium |
5 |
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 http://www.sherpa.ac.uk/romeo/issn/0363-6135/ |
en |
dc.rights.uri |
https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm |
en |
dc.subject |
cardiac thermodynamics heat-stress relationships dynamic stiffness diastolic calcium myofilament calcium sensitivity |
en |
dc.title |
Energetics of stress production in isolated cardiac trabeculae from rat |
en |
dc.type |
Journal Article |
en |
dc.identifier.doi |
10.1152/ajpheart.00454.2010 |
en |
pubs.begin-page |
H1382 |
en |
pubs.volume |
299 |
en |
dc.rights.holder |
Copyright: 2010 the American Physiological Society |
en |
dc.identifier.pmid |
20729397 |
en |
pubs.end-page |
H1394 |
en |
dc.rights.accessrights |
http://purl.org/eprint/accessRights/RestrictedAccess |
en |
pubs.subtype |
JOUR |
en |
pubs.elements-id |
152572 |
en |
pubs.org-id |
Bioengineering Institute |
en |
pubs.org-id |
ABI Associates |
en |
pubs.org-id |
Engineering |
en |
pubs.org-id |
Engineering Science |
en |
pubs.org-id |
Medical and Health Sciences |
en |
pubs.org-id |
Medical Sciences |
en |
pubs.org-id |
Physiology Division |
en |
pubs.org-id |
Science |
en |
pubs.org-id |
Science Research |
en |
pubs.org-id |
Maurice Wilkins Centre (2010-2014) |
en |
pubs.record-created-at-source-date |
2011-02-07 |
en |
pubs.dimensions-id |
20729397 |
en |