Hepatic adenine nucleotides measured by HPLC in mice following (A) a 5- or 18-hour fast (n = 6–8/group), (B) maximal treadmill exercise (starting at 10 m/min, adding 4 m/min every 3 minutes, after a 5-hour fast; n = 6–8/group), (C) insulin-induced hypoglycemic clamp (n = 6–8/group), and (D) with STZ-induced diabetes (1 s.c. injection of 150 mg/kg; n = 6/group) or fed a high-fat diet (HFD; 60% fat by kcal for 9 weeks) and after fasting for 5 hours (n = 4/group). Hepatic AMP/ATP ratios are also shown for each condition. TAN content is the sum total of ATP, ADP, and AMP. All mice were 12 weeks of age and on a C57BL/6 background except in the experiments shown in C, in which 129X1/Sv mice were also studied. Mice were compared with respective controls (fed, C57BL/6, and 5-hour-fasted chow-fed mice). Data are presented as mean ± SEM. *P < 0.05 compared with controls. †P < 0.05 compared with 5-hour-fasted mice.