title: Stress development, heat production and dynamic modulus of rat isolated cardiac trabeculae revealed in a flow-through micro-mechano-calorimeter.
abstract: Progress toward understanding the thermo-mechanical behavior of isolated cardiac muscle, excised from either healthy or diseased heart, is contingent on being able to measure simultaneously the stress (force per cross-sectional area) and heat production. Determination of dynamic modulus (dynamic stiffness times muscle length per cross-sectional area) sheds further light on the behavior of the force-and heat-generating actin-myosin cross-bridges. We are in a unique position to perform such measurements, given the recent completion of a micro-mechano-calorimeter. In this paper, we characterize the micro-mechano-calorimeter and present experimental results of twitch stress, heat per twitch and dynamic modulus measured in rat right-ventricular trabeculae at varied stimulus frequencies and muscle lengths. The minute radial dimensions of cardiac trabeculae (which approximate those of a human hair) ensure adequate provision of oxygen and nutrients via diffusion from the continuously replenished superfusate flowing through the measurement chamber. This enables investigation of the thermo-mechanical performance of cardiac trabeculae for many hours.
authors.affiliation: Auckland Bioengineering Institute and the Department of Engineering Science at The University of Auckland, New Zealand. a.taberner@auckland.ac.nz
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Taberner
authors.forename: June-Chiew
authors.initials: JC
authors.lastname: Han
authors.forename: Robert S
authors.initials: RS
authors.lastname: Kirton
authors.forename: Denis S
authors.initials: DS
authors.lastname: Loiselle
authors.forename: Poul M F
authors.initials: PM
authors.lastname: Nielsen
mesh_terms: D000199:Actins / Q000737:chemistry; D000465:Algorithms; D000818:Animals; D002151:Calorimetry / Q000379:methods*; D003432:Cross-Linking Reagents / Q000737:chemistry; D004548:Elasticity; D004867:Equipment Design; D006339:Heart Rate; D006358:Hot Temperature; D009206:Myocardium / Q000473:pathology*; D009218:Myosins / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical
chemical_list: D000199:Actins; D003432:Cross-Linking Reagents; D009218:Myosins; D010100:Oxygen