Transport and metabolism of pyridoxine in rat liver |
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Authors: | Haile Mehansho Daniel D. Buss Michael W. Hamm LaVell M. Henderson |
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Affiliation: | Department of Biochemistry, University of Minnesota, 1479 Gortner Avenue, St. Paul, MN 55108, U.S.A. |
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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 μM), the 3H of [3H]pyridoxine accumulated against a concentration gradient, but high concentrations (333 μM) 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. |
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Keywords: | Pyridoxine transport Vitamin B-6 Pyridoxine metabolism (Rat liver) |
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