The nomenclature for the 6 active B6 vitamers (B6) and related compounds is that of the IUPAC-IUB Commission of Biochemical Nomenclature (Eur. J. Biochem. (1973) 40. 325–327). The 6 active forms are pyridoxine. pyridoxal. pyridoxamine, pyridoxine 5′-phosphate (pyri-doxine-P), pyridoxal 5′-phosphate (pyridoxal-P), and pyridoxamine 5′-phosphate (pyridoxamine-P). The principal inactive metabolites of B6 are pyridoxic acid and pyridoxic acid lactone.
THE STABILITY OF VITAMIN B6 ACCUMULATION AND PYRIDOXAL KINASE ACTIVITY IN RABBIT BRAIN AND CHOROID PLEXUS
Article first published online: 5 OCT 2006
Journal of Neurochemistry
Volume 31, Issue 6, pages 1403–1410, December 1978
How to Cite
Spector, R. and Shikuma, S. N. (1978), THE STABILITY OF VITAMIN B6 ACCUMULATION AND PYRIDOXAL KINASE ACTIVITY IN RABBIT BRAIN AND CHOROID PLEXUS. Journal of Neurochemistry, 31: 1403–1410. doi: 10.1111/j.1471-4159.1978.tb06565.x
- Issue published online: 5 OCT 2006
- Article first published online: 5 OCT 2006
- Received 4 April 1978. Accepted 9 June 1978
The effects of changes in the concentrations of pyridoxal phosphate and blogenic amines in brain on: (I) pyridoxal kinase (EC 188.8.131.52) activity in brain and choroid plexus; and (2) vitamin B6 accumulation by brain slices and isolated, intact choroid plexuses were studied. New Zealand white rabbits were treated parenterally with 200 mg/kg pyridoxine-HCl for 3 days or 120 mg/kg 4-deoxypyridoxine HCI or 5 mg/kg reserpine I day before death. After these treatments the mean concentration of pyridoxal phosphate in brain was elevated by 39% by pyridoxine and decreased by 57% by 4-deoxypyridoxine. Reserpine had no effect. However, the ability of brain slices and isolated, intact choroid plexuses from the treated rabbits to accumulate [3H] vitamin B6 (with [3H]pyridoxine in the medium) was not different from untreated controls. Also, the specific activity of pyridoxal kinase in brain and choroid plexus of treated rabbits was not different from controls. These results show that vitamin B6 accumulation and pyridoxal kinase activity in brain and choroid plexus are independent of both pyridoxal phosphate and reserpine-sensitive biogenic amine concentrations in brain. In vitro studies with pyridoxal kinase showed that. in both choroid plexus and brain. pyridoxal kinase was a single enzyme with a molecular weight of 43.000 and a Km, for pyridoxine of 2.0 μM Crude and partially-purified pyridoxal kinase from brain was not inhibited by biogenic amines (1 mM) or pyridoxal phosphate (5 μM). These in vitro data are consistent with the lack of effect of changes in pyridoxal phosphate and biogenic amine concentrations (in brain) on pyridoxal kinase activity in brain in vivo.