FIGURE 4.

Dynamic changes of tryptophan and tryptophan metabolites after simulation of a tryptophan load test in the presence of vitamin B-6 deficiency. The tryptophan load was simulated as described in Figure 3. Vitamin B-6 deficiency was simulated by decreasing PLP concentration to 5% of the normal value in the model. The word “out” denotes urinary metabolites. AA, anthranilic acid; bptrp, tryptophan in peripheral circulation; gut, tryptophan in gut; HaA, 3-hydroxyanthranilic acid; HK, 3-hydroxykynurenine; hptrp, tryptophan in portal circulation; KA, kynurenic acid; Kyn, kynurenine; Ltrp, tryptophan in liver; Mtrp, tryptophan in muscle; QA, quinolinic acid; PLP, pyridoxal 5′-phosphate; XA, xanthurenic acid.