Spector R, Mock D
J Neurochem. 1987 Feb;48(2):400-4. doi: 10.1111/j.1471-4159.1987.tb04107.x.
The unidirectional influx of biotin across cerebral capillaries, the anatomical locus of the blood-brain barrier, was measured with an in situ rat brain perfusion technique employing [3H]biotin. Biotin was transported across the blood-brain barrier by a saturable system with a one-half saturation concentration of approximately 100 microM. The permeability-surface area products were 10(-4) s-1 with a biotin concentration of 0.02 microM in the perfusate. Probenecid, pantothenic acid, and nonanoic acid but not biocytin or biotin methylester (all 250 microM) inhibited biotin transfer through the blood-brain barrier. The isolated rabbit choroid plexus was unable to concentrate [3H]biotin from medium containing 1 nM [3H]biotin. These observations provide evidence that: biotin is transported through the blood-brain barrier by a saturable transport system that depends on a free carboxylic acid group, and the choroid plexus is probably not involved in the transfer of biotin between blood and cerebrospinal fluid.
采用[3H]生物素的原位大鼠脑灌注技术，测量了生物素在脑毛细血管（血脑屏障的解剖学部位）的单向流入。生物素通过一个饱和系统穿过血脑屏障，其半饱和浓度约为100微摩尔。当灌注液中生物素浓度为0.02微摩尔时，通透表面积乘积为10^(-4) s^(-1)。丙磺舒、泛酸和壬酸（生物胞素或生物素甲酯浓度均为250微摩尔时无此作用）抑制生物素通过血脑屏障的转运。分离的兔脉络丛无法从含有1纳摩尔[3H]生物素的培养基中浓缩[3H]生物素。这些观察结果提供了以下证据：生物素通过一个依赖游离羧酸基团的饱和转运系统穿过血脑屏障，并且脉络丛可能不参与生物素在血液和脑脊液之间的转运。
