title: Multiscale measurement of cardiac energetics.
abstract: Herein we describe our laboratories' experimental methods for interrogating cardiac energetics at the organ (whole heart), tissue (trabecula) and perforated fibre (mitochondrial) levels. In whole heart and trabecula experiments, we focus on measuring pressure-volume (force-length) work and oxygen consumption (heat production) from which mechanical efficiency is derived. In both preparations (i.e. across scales differing by three orders of magnitude) we find efficiency values of 10%-15%. Mitochondrial experiments invoke a trio of titration protocols to yield information on oxygen consumption, ATP flux, membrane potential, electron leak and reactive oxygen species production, the latter two of which index energy transfer inefficiencies.
authors.affiliation: Department of Physiology, The University of Auckland, Auckland, New Zealand.
authors.forename: Soyeon
authors.initials: S
authors.lastname: Goo
authors.forename: Toan
authors.initials: T
authors.lastname: Pham
authors.forename: Jun-Chiew
authors.initials: JC
authors.lastname: Han
authors.forename: Poul
authors.initials: P
authors.lastname: Nielsen
authors.forename: Andrew
authors.initials: A
authors.lastname: Taberner
authors.forename: Anthony
authors.initials: A
authors.lastname: Hickey
authors.forename: Denis
authors.initials: D
authors.lastname: Loiselle
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004583:Electrons; D004735:Energy Transfer / Q000502:physiology*; D006321:Heart / Q000502:physiology*; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D008928:Mitochondria / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate
keywords: ATP flux; cardiac enthalpy production; cardiac heat production; mitochondrial membrane potential; mitochondrial proton leak; mitochondrial reactive oxygen species production