Solving a century-old conundrum underlying cardiac force-length relations.

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dc.contributor.author Han, June en
dc.contributor.author Pham, Toan en
dc.contributor.author Taberner, Andrew en
dc.contributor.author Loiselle, Denis en
dc.contributor.author Tran, Kenneth en
dc.date.accessioned 2020-01-12T22:52:29Z en
dc.date.issued 2019-04 en
dc.identifier.citation American journal of physiology. Heart and circulatory physiology 316(4):H781-H793 Apr 2019 en
dc.identifier.issn 0363-6135 en
dc.identifier.uri http://hdl.handle.net/2292/49604 en
dc.description.abstract In the late 19th century, Otto Frank presented a diagram (Frank O. Z Biol 37: 483-526, 1899) showing that cardiac end-systolic pressure-volume relations are dependent on the mode of contraction: one for isovolumic contractions that locate above that for afterloaded ejecting contractions. Conflicting results to Frank's have been subsequently demonstrated in various species, both within and among preparations, ranging from the whole hearts to single myocytes, showing a single pressure-volume or force-length relation that is independent of the mode of contraction. Numerous explanations for these conflicting results have been proposed but are mutually contradictory and hence unsatisfying. The present study aimed to explore how these conflicting findings can be reconciled. We thus explored the cardiac force-length relation across a wide spectrum of both preloads and afterloads, encompassing the physiological working range. Experiments were performed using isolated ventricular trabeculae at physiological temperature and stimulus frequency. The force-length relation obtained from isometric contractions was indeed located above a family of those obtained from shortening contractions. Low preload conditions rendered the relation contraction mode independent. High afterload conditions also showed a comparable effect. Our exploration allowed us to reveal the loading conditions that can explain the apparent single, contraction mode-independent, force-length relation that is in contrast with that presented by Frank. Resolving this century-old cardiac conundrum highlights the caution that must be taken when using the end-systolic force-length relation to illustrate as well as to understand the concepts of the Frank-Starling law of the heart, "potential energy," and cardiac contractility. NEW & NOTEWORTHY Our exploration of the cardiac force-length relation under wide ranges of preload and afterload has allowed us to reconcile conflicting results in the literature regarding its length dependency. We show that the relation is dependent on the mode of contraction but can appear to be otherwise under certain conditions. This finding highlights the need for caution when using the force-length relation to understand key concepts in cardiac physiology. en
dc.format.medium Print-Electronic en
dc.language eng 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. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.rights.uri https://www.physiology.org/author-info.permissions en
dc.subject Heart en
dc.subject Heart Ventricles en
dc.subject Myocytes, Cardiac en
dc.subject Animals en
dc.subject Rats en
dc.subject Rats, Wistar en
dc.subject Cell Size en
dc.subject Blood Pressure en
dc.subject Myocardial Contraction en
dc.subject Isometric Contraction en
dc.subject Male en
dc.subject In Vitro Techniques en
dc.title Solving a century-old conundrum underlying cardiac force-length relations. en
dc.type Journal Article en
dc.identifier.doi 10.1152/ajpheart.00763.2018 en
pubs.issue 4 en
pubs.begin-page H781 en
pubs.volume 316 en
dc.rights.holder Copyright: 2019 the American Physiological Society en
pubs.end-page H793 en
pubs.publication-status Published en
dc.rights.accessrights http://purl.org/eprint/accessRights/OpenAccess en
pubs.subtype Research Support, Non-U.S. Gov't en
pubs.subtype Journal Article en
pubs.elements-id 766454 en
pubs.org-id Bioengineering Institute en
pubs.org-id ABI Associates en
dc.identifier.eissn 1522-1539 en
pubs.record-created-at-source-date 2019-02-02 en
pubs.dimensions-id 30707611 en


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