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NIACIN AND NIACINAMIDE ACCUMULATION BY RABBIT BRAIN SLICES AND CHOROID PLEXUS IN VITRO
Author(s) -
SPECTQR REYNOLD,
KELLEY PAUL
Publication year - 1979
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.1471-4159.1979.tb11731.x
Subject(s) - choroid plexus , niacin , niacinamide , nicotinamide , choroid , in vitro , chemistry , incubation , endocrinology , nad+ kinase , biochemistry , medicine , biology , central nervous system , retina , neuroscience , enzyme
The transport into and release of 14 C‐labeled niacin and niacinamide from rabbit brain slices and isolated choroid plexuses were studied. In vitro , both brain slices and choroid plexus concentrated 14 C by specific, energy‐dependent mechanisms when [ 14 C]niacinamide was added to the incubation medium. The saturable accumulation velocities, which were linear for 30 min, depended, in part, on incorporation of the [ 14 C]niacinamide into NAD. The X T and Y max for 14 C accumulation with [ 14 C]niacinamide in the medium by brain slices and choroid plexus were 0.80 μM and 1.45 μmolkg −1 (30 min) −1 , and 0.23 μM and 18.6 μmol kg −1 (30 min) −1 respectively. In vitro , the choroid plexus, unlike brain slices, vigorously concentrated 14 C by a separate, specific energy‐dependent process when 14 C niacin was added to the incubation medium. The saturable accumulation velocity, which was linear for 30 min, depended completely on the metabolism of [ 14 C]niacin. The K T and Y max for 14 C accumulation by choroid plexus with [ 14 C]niacin in the medium were 18.1 μM and 439 μmol kg −1 (30 min) −1 respectively. Whether preincubated in [ 14 C]niacin or [ 14 C]niacinamide, choroid plexus released predominantly [ 14 C]niacinamide.