Mechanism of fatty acid effect on myocardial oxygen consumption. A phosphorus NMR study.
The calorigenic effect of fatty acids on the intact myocardium was investigated in isolated rat hearts perfused with a phosphate-free bicarbonate buffer. 31P-NMR spectra were accumulated in a Fourier transform high-field spectrometer during titration of the heart with varying concentrations of hexanoate. Oxygen consumption, coronary flow, left ventricular pressure development, heart rate and tissue surface fluorescence of nicotinamide-adenine nucleotides were monitored simultaneously. It was found that hexanoate within a range of 40 to 800 microM increased the reduction of NADH/NAD, increased oxygen consumption and increased the phosphocreatine/inorganic phosphate ratio in a concentration-dependent manner. The results suggest that the fatty acid-induced increase in oxygen consumption is not due to a primary effect on the cellular energy state resulting from a decrease in the P/O ratio or uncoupling of the mitochondria but due to an increase in the thermodynamic driving force.
Department of Medical Biochemistry, University of Oulu, Finland.
I
I
Hassinen
K
K
Ito
S
S
Nioka
B
B
Chance
D000818:Animals; D004734:Energy Metabolism / Q000187:drug effects; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008433:Mathematics; D008962:Models, Theoretical; D009206:Myocardium / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects*; D010477:Perfusion; D010758:Phosphorus; D051381:Rats; D011919:Rats, Inbred Strains
D009243:NAD; D010758:Phosphorus; D009249:NADP