This inhibitory trend was maintained after cessation of juglone infusion. Fig. 3B allows an evaluation of the effects of several juglone concentrations on oxygen uptake and glucose production from lactate in the range of 5.0–50 μM. The final values observed at the end of the juglone infusion period (60 min perfusion time) were represented against the juglone concentrations. Glucose learn more production was inhibited over the whole range of the juglone concentrations. Numerical
interpolation revealed 50% inhibition at the juglone concentration of 14.9 μM. Oxygen uptake, on the other hand, was stimulated by juglone up to 20 μM, with maximal stimulation at 5 μM. Inhibition occurred at 50 μM, as also shown in Fig. 3A. Alanine gluconeogenesis was also investigated. This substrate induces
a more oxidized state when compared to lactate BLZ945 concentration and the transfer of the amine group also influences the urea cycle and several related pathways. Fig. 4A shows the effects of 50 μM juglone on the carbon fluxes and oxygen uptake due to alanine infusion whereas Fig. 4B illustrates the changes in the nitrogen fluxes. The infusion of 2.5 mM alanine caused a rapid increase in glucose production and oxygen uptake (Fig. 4A). The subsequent infusion of 50 μM juglone was strongly inhibitory for glucose production. Oxygen consumption underwent an initial transitory increase that was reversed to inhibition at 60 min perfusion time (Fig. 4A). Finally, 50 μM juglone strongly stimulated lactate and pyruvate production. The nitrogen fluxes were also
affected (Fig. 4B). Ammonia and glutamate production Pyruvate dehydrogenase were both clearly stimulated by the drug. Urea production underwent an initial transitory increase, which was followed by inhibition. The concentration dependences of the juglone effects on alanine metabolism are shown in Fig. 5. Inhibition of glucose production presents a clear concentration dependence, with 50% inhibition at the concentration of 15.7 μM. Stimulations of ammonia and glutamate productions were saturable functions of the juglone concentration in the range up to 50 μM, with half-maximal stimulations at 4.15 and 5.1 μM, respectively. Lactate and urea production were stimulated in the range up to 20 μM, with a declining tendency at 50 μM. Oxygen uptake was also stimulated by juglone up to 20 μM, but diminished to values below the basal ones at the concentration of 50 μM. Pyruvate production, finally, was stimulated over the whole concentration range with a parabolic dependence. For the sake of comparison the experiments with alanine as the substrate were repeated using the classical uncoupler 2,4-dinitrophenol (experiments not shown). The effects of this compound were similar to the actions of juglone. Gluconeogenesis was 50% inhibited at a concentration of 17.9 μM. Ammonia release and urea production were also stimulated by 2,4-dinitrophenol, with half-maximal effects at 4.55 and 4.76 μM, respectively.