Oxygen consumption of mouse left ventricular myocardial slices at rest and contraction under mechanically unloaded conditions

Abstract

Left ventricular (LV) mouse myocardial slices of the 300-μm thick freely shortened by 1-Hz electrical field stimulation. Mean myocardial slice oxygen consumption per minute (VO2) without stimulation was 0.97 ± 0.14 ml O2.min-1.100 g LV-1 and mean VO2 with stimulation increased to 1.80 ± 0.17 ml O2.min-1. 100 g LV-1 in normal Tyrode solution. Mean delta VO2 was 0.83 ± 0.12 ml O2.min-1.100 g LV-1. Cyclopiazonic acid 30 μM significantly reduced the delta VO2 to 33% of control. The increases in extracellular Ca concentrations up to 14.4 mM significantly increased the delta VO2 to 190% of control. BDM 3-5 mM decreased the delta VO2 by 33-37% of control not in a dose-dependent manner, though BDM 3-5 mM dose-dependently decreased the slice free shortening. Present results indicate the possibility that the VO2 of mouse LV slices during shortening under mechanically unloaded conditions consists of energy expenditure for total Ca handling in the excitation-contraction coupling, basal metabolism and possibly definite residual crossbridge cycling (maximally 33% of control). [Jpn J Physiol 54 Suppl:S106 (2004)]