Biotin and biocytin uptake into cultured primary calf brain microvessel endothelial cells of the blood-brain barrier
Biotin and biocytin uptake into cultured primary calf brain microvessel endothelial cells of the blood-brain barrier
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DOI：
10.1016/s0006-8993(00)01944-2
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发表时间：
2000-03-10
期刊：
影响因子：
2.9
通讯作者：
Baumgartner, ER
中科院分区：
文献类型：
--
作者：
Baur, B;Baumgartner, ER
在牛脑微血管内皮（CBME）细胞的原代培养物中，生物素和密切相关的生物胞素的摄取被表征。生物素的摄取被认为是Na+-梯度依赖性和独立的膜电位的变化。浓度依赖性揭示了一个单一的饱和机制与47 μ M的Km和V-最大值为101 pmol/min/mg。抑制研究表明，依赖于代谢能和运输活动的自由羧基的必要性。抗惊厥药扑米酮和卡马西平无抑制作用。CBME细胞对生物素的摄取是一个次级活性、电中性、可饱和和特异性的过程。在生物素酶缺乏症（一种人类先天性疾病）中积累的生物胞素不抑制生物素摄取，也不转运到这些细胞中。具有正常生物素酶活性的人血清的存在使生物素摄取显著降低约50%。此外，添加的生物胞素水解为生物素，其在细胞内积累，但程度低于添加的游离生物素。加入生物素酶缺乏患者血浆后的生物素摄取与正常血清存在下的生物素摄取没有差异。这些结果表明，血清中缺乏生物素酶活性不会降低生物素的血脑屏障转运。(C)2000爱思唯尔科技有限公司。保留所有权利。
The uptake of biotin and the closely related biocytin was characterized in primary cultures of calf brain microvessel endothelial (CBME) cells. Biotin uptake was found to be Na+-gradient dependent and independent of changes in the membrane-potential. Concentration dependence revealed a single saturation mechanism with a K-m of 47 mu M and a V-max of 101 pmol/min/mg. Inhibition studies demonstrated dependence on metabolic energy and the necessity for a free carboxyl group for transport activity. The anticonvulsants primidone and carbamazepine had no inhibitory effect. Biotin uptake into CBME cells is a secondary active, electroneutral, saturable and specific process. Biocytin which accumulates in biotinidase deficiency, a human congenital disorder, did not inhibit biotin uptake and was not transported into these cells. The presence of human serum with normal biotinidase activity significantly reduced biotin uptake by about 50%. Further, added biocytin was hydrolyzed to biotin, which accumulated intracellularly but to a lesser extent than added free biotin. Biotin uptake after addition of plasma of biotinidase-deficient patients was not different from that in the presence of normal serum. These results indicate that the absence of biotinidase activity in serum does not reduce blood-brain barrier transport of biotin. (C) 2000 Elsevier Science B.V. All rights reserved.