Lumiflavin and lumichrome transport in the central nervous system.
The transport of the lipid-soluble sugarless flavins, [14C]lumiflavin and [14C]lumichrome, into an 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]lumichrome 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 mumol 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.
D000818:Animals; D001692:Biological Transport; D001921:Brain / Q000378:metabolism*; D002831:Choroid Plexus / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism; D005486:Flavin Mononucleotide / Q000502:physiology; D005415:Flavins / Q000378:metabolism*; D066298:In Vitro Techniques; D011817:Rabbits; D012256:Riboflavin / Q000502:physiology
D005415:Flavins; C001559:7,8-dimethylalloxazine; C001922:lumiflavin; D005486:Flavin Mononucleotide; D012256:Riboflavin