Effect of fasting and acute ethanol administration on the energy state of in vivo liver as measured by 31P-NMR spectroscopy

Abstract

The effects of 48 h fasting, administration of ethanol or 2,4-dinitrophenol, on the phosphorus-containing metabolites in liver in vivo have been determined utilizing 31P nuclear magnetic resonance spectroscopy. These measurements were combined with determinations of metabolite concentrations in livers which were freeze-clamped immediately after the NMR measurements were completed. Administration of sub-lethal amounts of dinitrophenol dramatically decreased ATP and increased P i concentrations in liver in vivo as indicated by a 2.7-fold increase in the NMR-derived [ P i ] [ ATP] ratio. Ethanol administration to fed animals increased the NMR-derived [ P i ] [ ATP] ratio 27%; in contrast, the same amount of ethanol administered to fasted animals decreased the NMR-derived [ P i ] [ ATP] ratio 30%. The NMR visible P i and ADP represent about 50% and 15% of the total P i and ADP, respectively. The phosphorylation potentials calculated from the NMR visible P i and ADP were an order of magnitude higher than those obtained from metabolite concentrations in freeze-clamped tissue. There was no apparent correlation between the phosphorylation potentials derived from either the NMR spectral analyses or from metabolite concentrations and the hepatic [ NAD +] [ NADH] ratio. The chemical shift of P i indicated that ethanol administration elicited a decrease in pH of 0.1 unit in liver in vivo. Hepatic free [Mg 2+] was increased 21% in fasted animals, but was unaffected by ethanol administration.