Effect of adenine on liver nucleotide after fructose loading by 31P-NMR

Livers from 125- to 150-g rats were perfused and the effect of fructose metabolism on liver energetics was observed using 31P nuclear magnetic resonance (NMR). Livers were exposed to fructose in a nonrecirculating manner for approximately 15 min and monitored for recovery for 30 min. At concentrations ranging from 1 to 25 mM, fructose exposure led to depletion of the nucleoside triphosphate level. Subsequently, the nucleoside triphosphate level recovered fully at a fructose concentration of 1 mM; however, recovery was only 65% of the initial values if the fructose concentration was 10 mM and 55% if the concentration was 25 mM. Adenine was found to protect nucleoside triphosphate levels against the adverse effects of fructose by blocking the deamination of AMP. In the presence of adenine, AMP accumulation was observed in the NMR spectra upon exposure of the liver to fructose.