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Vitamin B 6 Metabolism and Binding to Proteins in the Blood of Alcoholic and Nonalcoholic Men
Author(s) -
Fonda Margaret L.
Publication year - 1993
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.1993.tb05223.x
Subject(s) - pyridoxal , pyridoxine , incubation , chemistry , pyridoxal phosphate , medicine , metabolism , endocrinology , biochemistry , vitamin , blood proteins , blood plasma , enzyme , cofactor
Blood obtained from nonalcoholic and alcoholic subjects was incubated with 100 n m [ 3 H]pyridoxine to study its uptake and metabolism by erythrocytes and the binding of vitamin B 6 metabolites to proteins in plasma and erythrocytes. Erythrocytes of the alcoholics accumulated tritium faster than those of the controls; however, they contained the same total amount of tritiated compounds by 15 min. After incubation for 30 min, the erythrocytes had converted most of the pyridoxine to pyridoxal phosphate and pyridoxal. Pyridoxal‐P remained in the erythrocytes, and ?40% of the pyridoxal diffused into the plasma. [ 3 H]Pyridoxal and [ 3 H]pyridoxal‐P levels in the erythrocytes and plasma of the alcoholics were similar to those in the controls. However, dialyzed hemolysates of the alcoholics had more [ 3 H]pyridoxal and a lower percentage of [ 3 H]pyridoxal‐P than those of the controls. The total concentration of plasma pyridoxal‐P was lower in the alcoholics than in the controls and did not change upon incubation of whole blood with pyridoxine or upon dialysis. The erythrocytes of the alcoholics and controls had similar concentrations of pyridoxal‐P that increased 2.5‐fold upon incubation of whole blood with pyridoxine for 30 min and returned to the initial concentrations upon dialysis. The amount of [ 3 H]pyridoxal and [ 3 H]pyridoxal‐P bound to protein was assessed by treating hemolysate and plasma samples with borohydride before dialysis. More 3 H was bound to protein in the erythrocytes than in the plasma. The amount of protein‐bound 3 H in the erythrocytes of the alcoholics was lower than that of the controls, whereas the amount of protein‐bound 3 H in plasma was similar in both groups. It is concluded that less of the pyridoxal‐P and pyridoxal was protein bound, and the pyridoxal‐P was more susceptible to hydrolysis to pyridoxal by phosphatases in the erythrocytes of the alcoholics compared with the controls.