CELLULAR MECHANISMS OF DRUG TRANSPORT IN CHOROID PLEXUS

脉络丛药物转运的细胞机制

• 批准号: 2181280
• 负责人: KATHLEEN M GIACOMINI
• 金额: $ 13.6万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-01-01 至 1994-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2181280
• 关键词: Parkinson's disease; antiparkinson drugs; basolateral membrane; cations; choroid plexus; dopamine; drug delivery systems; drug metabolism; electrical potential; electrophysiology; epinephrine; histamine; membrane potentials; membrane transport proteins; neuropharmacology; norepinephrine; proline; serotonin; sodium; Parkinson's disease; antiparkinson drugs; basolateral membrane; cations; choroid plexus; dopamine; drug delivery systems; drug metabolism; electrical potential; electrophysiology; epinephrine; histamine; membrane potentials; membrane transport proteins; neuropharmacology; norepinephrine; proline; serotonin; sodium

The organic cation transport system in choroid plexus epithelium functions as part of the "blood-cerebral spinal fluid barrier" in regulating the concentrations of various organic cations in the cerebral spinal fluid (CSF and thus the extracellular fluids of the brain. The overall goals of the proposed studies are to elucidate the molecular events involved in the transport of organic cations across the choroid plexus epithelial cells. T attain these goals, sequential studies will be carried out on isolated plasma membrane vesicles and in cultured bovine choroid plexus epithelial cells. First, the molecular events involved in the transport of organic cations across the individual plasma membranes will be studied using isolated brush border and basolateral membrane vesicles prepared from choroid plexus epithelium. It will be determined whether there are specific, saturable transport mechanisms in each membrane. Afterwards, the electrogenecity of the transport across each membrane will be determined to obtain information about whether organic cations may be accompanied with anions or may exchange with cations during the transport process across the individual membranes. Next, studies will be carried out to identify a possible driving force for organic cation transport. It is hypothesized that active organic cation transport is secondarily active and thus driven by an ion gradient across one membrane. Several models are being proposed. For example, in one model it is proposed that organic cations are transported across the brush border membrane by a passive, facilitated process and accumulate in choroid plexus cells as a result of the favorable potential difference. Transport across the basolateral membrane is necessarily active and involves a sodium exchange mechanism. Finally, studies will be carried out to determine whether the transporter in each membrane functions as a simple pore or a mobile carrier. The studies in cultured choroid plexus epithelium are designed to address questions relate to the active accumulation of organic cations in intact epithelium. First, the studies will determine whether organic cations are accumulated in the cells by active, saturable and structurally specific mechanisms. Then usin monolayers of the cultured epithelial cells placed in flux chambers, the preferred membrane (brush border or basolateral) through which organic cations are transported into and out of the cell will be identified. It is hypothesized that organic cations are actively transported from CSF to blood; thus, the brush border (ventricular) membrane would be the preferred membrane for influx and the basolateral (serosal) membrane would be preferred for efflux. Studies of transepithelial flux across the cultured monolayers will be carried out to elucidate the vectorial direction of net organic cation flux. The relevance of the findings in the vesicles to transport across the intact cell will be elucidated. N1-methylnicotinamide and choline will be used as model organic cations and the methods will involve isotopic techniques with the tritiated compounds. Clinically many important drugs as well as potent endogenous compounds including various neurotransmitters and toxins are transported by the choroid plexus. Transport via this system ultimately controls the concentrations of many basic compounds in the CSF and thus, may influence their biologic effects. For example, the use of lidocaine, a clinically important antiarrhythmic agent, is limited by its neurological toxicities. Transport in the choroid plexus may control the concentrations of lidocaine in the cerebral spinal fluid thereby influencing the neurological toxicities. Recently, it has been hypothesized that the organic cation transport system of the choroid plexus may play a role in the etiology of Parkinson's Disease. These studies will ultimately lead to a more rational use of drugs and to an enhanced awareness of the mechanisms involved in the transport of biologically active organic cations across the "blood-CSF-barrier".

脉络丛上皮功能中的有机阳离子传输系统 作为调节 大脑脊髓液中各种有机阳离子的浓度（CSF 因此，大脑的细胞外流体。 总体目标 拟议的研究是为了阐明参与的分子事件 有机阳离子在脉络丛上皮细胞中的转运。 t 达到这些目标，将在孤立的 质膜囊泡和培养的牛脉络丛上皮 细胞。 首先，有机运输涉及的分子事件 将使用单个质膜的阳离子进行研究 由孤立的刷子边框和基底外侧膜囊泡制备 脉络丛上皮。 将确定是否有 每个膜中的特定饱和运输机制。 之后， 跨每个膜的运输的电源将确定为 获取有关是否可能伴有有机阳离子的信息 阴离子或可能在横跨运输过程中与阳离子交换 单个膜。 接下来，将进行研究以确定 有机阳离子运输的可能驱动力。 它是假设的 主动有机阳离子的运输是第二个活动性的，因此驱动 通过一个跨膜的离子梯度。 正在提出几种模型。 例如，在一个模型中，有人提出有机阳离子是 通过被动的，便利地在刷子边界膜上运输 由于有利 潜在差异。 穿过基底外侧膜的运输是 一定有效，涉及钠交换机制。 最后， 将进行研究以确定每个转运蛋白是否在每个 膜充当简单的孔或移动载体。 研究 培养的脉络丛上皮旨在解决问题 有机阳离子在完整上皮的活性积累。 第一的， 研究将确定是否积累了有机阳离子 通过主动，饱和和结构特异性机制的细胞。 然后usin 培养的上皮细胞的单层，放在通量腔中， 首选膜（刷边框或基底外侧）有机 阳离子将被鉴定出进入和出口。 这是 假设有机阳离子是从CSF积极运输的 血;因此，刷边框（心室）膜将是首选 涌入的膜和基底外侧（浆膜）膜将是 首选排出。 跨培养的跨层通量的研究 将进行单层以阐明净的矢量方向 有机阳离子通量。 囊泡中发现的相关性与 跨完整细胞的运输将被阐明。 N1-甲基二酰胺 胆碱将用作模型有机阳离子，方法将 涉及与曲折化合物的同位素技术。 临床上很多 重要的药物以及有效的内源化合物，包括各种 神经递质和毒素由脉络丛转运。 通过该系统运输最终控制着许多 CSF中的基本化合物可能会影响其生物学作用。 例如，使用利多卡因（一种临床上重要的抗心律失常） 特工受到其神经毒性的限制。 脉络膜运输 丛可能控制脑脊髓中利多卡因的浓度 液体因此影响神经毒性。 最近，它有 假设脉络膜的有机阳离子运输系统 丛可能在帕金森氏病的病因中发挥作用。 这些 研究最终将导致更合理地使用药物，并 提高了对运输所涉及的机制的认识 跨“血液-CSF - 障碍物”的生物活性有机阳离子。