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VITAMIN B 6 TRANSPORT IN THE CENTRAL NERVOUS SYSTEM: IN VIVO STUDIES
Author(s) -
Spector Reynold
Publication year - 1978
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1978.tb10797.x
Subject(s) - choroid plexus , cerebrospinal fluid , endocrinology , in vivo , medicine , central nervous system , chemistry , extracellular , choroid , blood–brain barrier , biology , biochemistry , retina , microbiology and biotechnology , neuroscience
— The total concentrations of vitamin B 6 (B 6 ) in plasma, choroid plexus, CSF and brain of adult New Zealand white rabbits, measured fluorometrically, were 0.30, 15.10, 0.39 and 8.90 μ mol/l or kg respectively. The mechanisms by which B 6 enters and leaves brain, choroid plexus and CSF were investigated by injecting [ 3 H]pyridoxine (PIN) intravenously, intraventricularly and intraarterially. [ 3 H]PIN, with or without unlabelled PIN, was infused intravenously at a constant rate into conscious rabbits. At 150 min, [ 3 H]B 6 readily entered CSF, choroid plexus and brain. The addition of 0.5 mmol/kg carrier PIN to the infusion solution depressed the relative entry of [ 3 H]B 6 into CSF, choroid plexus and brain by about 80%. After intraventricular injection, [ 3 H]PIN readily entered brain from CSF. The intraventricular injection of carrier PIN with [ 3 H]PIN decreased the amount of [ 3 H]B 6 in brain and also decreased the percentage of [ 3 H]B 6 in CSF and brain that was phosphorylated. During one pass through the cerebral circulation, [ 3 H]PIN (1 μ m ) was cleared from the circulation no more rapidly than mannitol. These results were interpreted as showing that the entry of B 6 from blood into CSF and presumably the extracellular space of brain and thence into brain cells involves one or more saturable transport and/or metabolic steps.