B-6 vitamer concentrations in mouse plasma, erythrocytes and tissues

Abstract

The five major forms of vitamin B-6, pyridoxal 5'-phosphate (PLP), pyridoxal (PL), pyridoxamine (PM), pyridoxamine 5'-phosphate (PMP) and pyridoxine (PN) were measured in plasma, erythrocytes, liver and brain of A/Ibg and DBA/2Ibg mice by paired-ion High Pressure Liquid Chromatography. The mice were fed a non-purified diet that provided the bioavailable equivalent of approximately 3–4 mg PN-HCl/kg diet. In each tissue two of the vitamers accounted for nearly all of the total concentration of vitamin B-6. These were: plasma, PLP (14%) and PL (85%); erythrocytes, PLP (94%) and PL (3%); liver, PLP (63%) and PMP (36%); and brain PLP (55%) and PMP (43%). PM and PN contributed negligible amounts to the total vitamin B-6 content of these tissues. There were no significant differences in the concentrations of any of the vitamers between the two mouse strains, however, Pearson correlations between pairs of indices were different in the two strains. For example, plasma and liver PLP concentrations were uncorrelated in the A, but negatively correlated in the DBA mice. These data suggest that although plasma PLP may be a suitable index of dietary intake of vitamin B-6, genetic factors may be an important variable in the ability to predict tissue concentrations of the B-6 vitamers from plasma or erythrocyte concentrations.