Plasma content of B-6 vitamers and its relationship to hepatic vitamin B-6 metabolism

governed by, anmong other factors, dietary supply anid metabolic interconversion. This study examines the ef-fect of pyridoxinie supplementation on the plasma con-tent of B6 vitaimers anid pyridoxic acid in man, and the metabolic conversioni aind releatse of B6 compounlds in isolated rat hepatocytes. Six healthy humiian sulbjects were givein 100n)mg pyridoxine-HCI/d orally for 1-3 wk. Before pyridoxine stupplemenetationi, the mean total plasma level of B6 vitamners was 114+9 nM; acnd ( pyri-doxal-P, pyridoxamine-P, pyridoxal, pyridoxine, aind pyridoxaminie accounted for 54, 3, 11, 27, ani(d 5%, re-spectively. Plasmna level of pyridoxic acid was 40±7 nM. Thus, pyridloxal-P is the principal B6 vitaimer in plasma. Durinig pyridoxine stupplemiienitation, mealn plasnma levels of the B6 vitaimers anid pyridoxic acid