Vitamin B6 Deficiency in Rats: Utilization of 14C-labeled glutamic acid and sodium 2-ketoglutarate

The effect of a vitamin B6 deficiency on the utilization of 14C-labeled glutamic acid and 2-ketoglutarate in brain and liver tissue was investigated. When glutamate-2-14C was injected the activity in the expired carbon dioxide from vitamin B6-depleted rats was less than that from the control rats. Three fractions were isolated from the brain and liver hydrolysates: 1) all amino acids minus glutamic and aspartic acid, 2) glutamic acid, and 3) aspartic acid. There was no difference in the proportion of 14C found in the 3 fractions isolated from the brains of the deficient group as compared with the control group except in the 14C activity of aspartic acid. In this instance the least 14C activity was noted in the pyridoxine-supplemented group. Liver amino acid fractions from the vitamin B6-deficient rats showed lower levels of 14C activity. Variable levels of 14CO2 were obtained upon injection of 2-ketoglutarate-3,5-14C. In the brain fractions 1 and 3 were significantly lower in the vitamin B6-deprived group than in the vitamin-supplemented group. The 3 fractions from vitamin B6-deficient livers showed lower levels of 14C activity than from the control rats, but the difference was only significant with fraction 3.