title: Myocardial energetics is not compromised during compensated hypertrophy in the Dahl salt-sensitive rat model of hypertension.
abstract: Salt-induced hypertension leads to development of left ventricular hypertrophy in the Dahl salt-sensitive (Dahl/SS) rat. Before progression to left ventricular failure, the heart initially undergoes a compensated hypertrophic response. We hypothesized that changes in myocardial energetics may be an early indicator of transition to failure. Dahl/SS rats and their salt-resistant consomic controls (SS-13(BN)) were placed on either a low- or high-salt diet to generate four cohorts: Dahl-SS rats on a low- (Dahl-LS) or high-salt diet (Dahl-HS), and SS-13(BN) rats on a low- (SSBN-LS) or high-salt diet (SSBN-HS). We isolated left ventricular trabeculae and characterized their mechanoenergetic performance. Our results show, at most, modest effects of salt-induced compensated hypertrophy on myocardial energetics. We found that the Dahl-HS cohort had a higher work-loop heat of activation (estimated from the intercept of the heat vs. relative afterload relationship generated from work-loop contractions) relative to the SSBN-HS cohort and a higher economy of contraction (inverse of the slope of the heat vs. active stress relation) relative to the Dahl-LS cohort. The maximum extent of shortening and maximum shortening velocity of the Dahl/SS groups were higher than those of the SS-13(BN) groups. Despite these differences, no significant effect of salt-induced hypertension was observed for either peak work output or peak mechanical efficiency during compensated hypertrophy.
authors.affiliation: Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand; k.tran@auckland.ac.nz.
authors.forename: Kenneth
authors.identifier: 0000-0002-8651-3557
authors.initials: K
authors.lastname: Tran
authors.affiliation: Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand;
authors.forename: June-Chiew
authors.initials: JC
authors.lastname: Han
authors.affiliation: Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand; Department of Engineering Science, University of Auckland, Auckland, New Zealand;
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Taberner
authors.affiliation: Department of Engineering Science, University of Auckland, Auckland, New Zealand;
authors.forename: Carolyn J
authors.initials: CJ
authors.lastname: Barrett
authors.affiliation: Systems Biology Laboratory, Melbourne School of Engineering, University of Melbourne, Parkville, Victoria, Australia; School of Mathematics and Statistics, University of Melbourne, Parkville, Victoria, Australia; and School of Medicine, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Edmund J
authors.initials: EJ
authors.lastname: Crampin
authors.affiliation: Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand; Department of Physiology, University of Auckland, Auckland, New Zealand;
authors.forename: Denis S
authors.initials: DS
authors.lastname: Loiselle
mesh_terms: D000818:Animals; D001794:Blood Pressure; D004039:Diet, Sodium-Restricted; D004195:Disease Models, Animal; D004734:Energy Metabolism; D006333:Heart Failure / Q000378:metabolism* / Q000503:physiopathology; D006973:Hypertension / Q000378:metabolism* / Q000503:physiopathology; D017379:Hypertrophy, Left Ventricular / Q000378:metabolism* / Q000503:physiopathology; D009200:Myocardial Contraction / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D020303:Rats, Inbred Dahl; D017673:Sodium Chloride, Dietary; D018487:Ventricular Dysfunction, Left / Q000378:metabolism / Q000503:physiopathology
chemical_list: D017673:Sodium Chloride, Dietary
keywords: Dahl salt-sensitive rat; compensated hypertrophy; hypertension; mechanical efficiency; myocardial energetics