title: Transport and metabolism of pyridoxine in rat liver.
abstract: Evidence, obtained with in situ perfused rat liver, indicated that pyridoxine is taken up from the perfusate by a non-concentrative process, followed by metabolic trapping. These conclusions were reached on the basis of the fact that at low concentrations (0.125 microM), the 3H of [3H]pyridoxine accumulated against a concentration gradient, but high concentrations (333 microM) of pyridoxine or 4-deoxypyridoxine prevented this apparent concentrative uptake. Under no conditions did the tissue water:perfusate concentration ratio of [3H]pyridoxine exceed unity. The perfused liver rapidly converted the labeled pyridoxine to pyridoxine phosphate, pyridoxal phosphate and pyridoxamine phosphate and released a substantial amount of pyridoxal and some pyridoxal phosphate into the perfusate. Since muscle and erythrocytes failed to oxidize pyridoxine phosphate to pyridoxal phosphate, it is suggested that the liver plays a major role in oxidizing dietary pyridoxine and pyridoxamine as their phosphate esters to supply pyridoxal phosphate which then reaches to other organs chiefly as circulating pyridoxal.
mesh_terms: D000042:Absorption; D000818:Animals; D001692:Biological Transport; D001834:Body Water / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008297:Male; D009132:Muscles / Q000378:metabolism; D010477:Perfusion; D011736:Pyridoxine / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D014316:Tritium
chemical_list: D014316:Tritium; D011736:Pyridoxine