The 31P NMR visibility of ATP in perfused rat liver remains about 90%, unaffected by changes of metabolic state.
The 31P NMR visibility of ATP of the perfused rat liver was tested over a wide range of metabolic conditions, including normoxic and hypoxic perfusions, fructose loads, and various intervals of normothermic ischemia, for both ad libitum fed and 24-h fasted rats. The 31P NMR signal of ATP was compared to the concentration of ATP determined by enzymatic assays on liver biopsies performed at the end of NMR acquisition. In a first series of experiments, the NMR resonance of intracellular ATP was quantitated in absolute terms by applying the 1H NMR water signal as internal reference: during normoxic and hypoxic perfusions, a constant amount of ATP (0.43 +/- 0.19 mM, mean +/- SD), approximately 12% of the cellular ATP, is not detected by NMR. Nevertheless, there is a high correlation (slope = 0.96 +/- 0.09; r2 = 0.93) between the measurements of ATP by 31P NMR spectroscopy and by biochemical analysis. In a second series of experiments, there was a highly significant correlation between the NMR and analytical biochemical measurements of ATP for whole range of metabolic states, i.e., fructose loads (1.0-10 mM) and various intervals of normothermic ischemia (ranging from 2 to 12 min), indicating unchanged ATP visibility. Thus, as opposed to the studies of Murphy et al. [Murphy, E., et al. (1988) Biochemistry 27, 526-528], it is concluded that ATP at 37 degrees C remains almost entirely visible in the perfused rat liver, also during ischemia.
Masson
S
S
Department of Biochemistry, Panum Institute, Copenhagen, Denmark.
Quistorff
B
B
D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000032:analysis / Q000378:metabolism*; D000818:Animals; D000860:Hypoxia / Q000378:metabolism; D007511:Ischemia / Q000378:metabolism; D008099:Liver / Q000098:blood supply / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D010477:Perfusion / Q000295:instrumentation / Q000379:methods; D010710:Phosphates / Q000378:metabolism; D010758:Phosphorus; D051381:Rats; D011919:Rats, Inbred Strains
D010710:Phosphates; D010758:Phosphorus; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate