title: Use of 2,3-butanedione monoxime to estimate nonmechanical VO2 in rabbit hearts.
abstract: The purpose of the present study was to evaluate the feasibility of partitioning myocardial O2 consumption (VO2) into mechanical and nonmechanical components in the whole heart preparation using a negative inotrope, 2,3-butanedione monoxime (BDM), which has been reported to have a selective effect on the contractile proteins in a low concentration range (< 6 mM). In six isolated bovine red blood cell-perfused rabbit hearts, VO2 and force-time integral (FTI) were measured during infusion of varying concentrations of BDM at a constant left ventricular volume chosen such that control left ventricular peak isovolumic pressure was approximately 100 mmHg. The VO2-FTI relation with BDM concentrations < or = 5 mM was highly linear (median r = 0.98). Its VO2-axis intercept at zero FTI had a positive value (mean 23% of control, 0.014 ml O2.beat-1 x 100 g-1). To confirm the selective effect of BDM on the contractile proteins, the intracellular free Ca2+ transient was measured with the fluorescent indicator indo 1 in three isolated buffer-perfused rabbit hearts. The amplitude of the Ca2+ transient was not altered by BDM at concentrations < or = 10 mM, although left ventricular developed pressure was markedly depressed. This finding indicates that BDM < or = 10 mM does not affect excitation-contraction coupling. We conclude that the VO2-axis intercept value of the VO2-FTI relation during BDM infusion in a low concentration range represents VO2 for nonmechanical energy utilization. The BDM method to partition VO2 into mechanical and nonmechanical components is thus feasible in the whole rabbit heart.
authors.affiliation: Cardiology Unit, College of Medicine, University of Vermont, Burlington 05405.
authors.forename: H
authors.initials: H
authors.lastname: Yaku
authors.forename: B K
authors.initials: BK
authors.lastname: Slinker
authors.forename: T
authors.initials: T
authors.lastname: Mochizuki
authors.forename: B H
authors.initials: BH
authors.lastname: Lorell
authors.forename: M M
authors.initials: MM
authors.lastname: LeWinter
mesh_terms: D000818:Animals; D003931:Diacetyl / Q000031:analogs & derivatives* / Q000494:pharmacology; D004734:Energy Metabolism; D005456:Fluorescent Dyes; D066298:In Vitro Techniques; D007211:Indoles; D008297:Male; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D009994:Osmolar Concentration; D010101:Oxygen Consumption / Q000187:drug effects*; D011817:Rabbits
chemical_list: D005456:Fluorescent Dyes; D007211:Indoles; C004717:diacetylmonoxime; D003931:Diacetyl; C048960:indo-1