Lumiflavin and Lumichrome Transport in the Central Nervous System |
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Authors: | Reynold Spector |
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Institution: | Departments of Medicine und Pharmacology, University of Iowa College of Medicine, Iowa City, Iowa 52242, U.S.A. |
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Abstract: | Abstract: The transport of the lipid-soluble sugarless flavins, 14C]lumiflavin and 14C]lumichrome, into and from the isolated choroid plexus and brain slices was studied in vitro. The isolated choroid plexus accumulated both 14C] flavins by a saturable, energy-requiring process that did not depend on binding or intracellular metabolism of the 14C] flavins. Both sugar-containing and sugarless flavins, as well as cyclic organic acids, significantly inhibited 14C]lumiflavin and 14C]Iumichrome uptake by the isolated choroid plexus. Within 2.5 min, 75% of the 14C]lumiflavin accumulated by the isolated choroid plexus was released into the medium. Brain slices accumulated 14C]lumiflavin by a saturable process that did not meet all the criteria for active transport. Ninety-five percent of the 14C]lumiflavin accumulated by brain slices was released into the medium within 7.5 min. In vivo , 2 h after the intraventricular injection of 6.5 nmol 14C]lumiflavin, almost all of the 14C]flavin was cleared from the CNS. Addition of 3.5 μmol FMN to the intraventricular injectate significantly decreased the clearance of 14C]lumiflavin from the CNS. These studies document that the sugarless flavins are transported by the flavin transport systems in the CNS. |
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Keywords: | Lumiflavin Lumichrome Transport Brain Choroid plexus Riboflavin |
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