ROLE OF ALTERED MEMBRANE FUNCTION IN XENOBIOTIC TOXICITY

有机阴阳离子(OC)的肾脏分泌系统起支配作用 消除大多数较小的(小于或等于500mol.wt.)国外 化学制品。我们之前已经证明，OA传输是间接的 通过Na/α-酮戊二酸(α-KG)协同作用与代谢能量偶联. 运输和OA/AlphaKG交换。我们目前正在检查a)血浆 与分泌转运相关的膜和细胞内事件(In 与D.S.Miller的合作)，b)这些系统的分子生物学， C)肾外OA和OC转运的能量学和机制，以及d) OA和OC在肾脏和肾外部位的毒理学研究我们有 开发了一种单层培养的内皮细胞和 血脑屏障的上皮性成分(脉络丛)。这些 体外系统能有效地转运骨钙素和骨钙素。此外，一旦在 细胞OC被吸收成膜小泡，随后 将其内容物释放到上皮的血液侧，这是一个过程 被诺可达唑引起的微管去极化干扰。一种类似的 过程中似乎参与了肾脏带电有机物质的分泌 外源生物也是。对大鼠肾小管的分级表明 肾脏α-KG主要局限于线粒体内部， 而细胞质α-KG是疗效的主要决定因素 肾脏骨性关节炎的转运和排出。最后，表达克隆和 用聚合酶链式反应探针筛选大鼠CDNA文库 肾脏中编码这两种重要排泄物的基因的mRNA 运输系统。我们已经确定了一个由pH驱动的克隆， 电位敏感型OC载体。目前正在对其进行测序。积极的一面 信号也存在于我们的图书馆中，用于OA传送器和筛查 也在进行隔离它的工作。

Renal secretory systems for organic anions (OA) and cations (OC) govern the elimination of most small (less than or equal to 500mol.wt.) foreign chemicals. We have previously shown that OA transport is indirectly coupled to metabolic energy through Na/alpha-ketoglutarate (alphaKG) co- transport and OA/alphaKG exchange. We are currently examining a) plasma membrane and intracellular events associated with secretory transport (in collaboration with D.S. Miller), b) molecular biology of these systems, c) energetics and mechanisms of extrarenal OA and OC transport, and d) toxicology of OA and OC in kidney and extrarenal sites. We have developed a monolayer cultured preparations for both endothelial and epithelial (choroid plexus) components of the blood-brain barrier. These systems actively transport OA and OC in vitro. In addition, once within the cells OC are taken up into membrane vesicles which subsequently release their contents on the blood side of the epithelium, a process disrupted by depolimerization of microtubules with nocodazole. A similar process appears to participate in renal secretion of charged organic xenobiotics as well. Fractionation of rat renal tubules has shown that renal alphaKG is largely confined to the interior of the mitochondria, and that cytoplasmic alphaKG is the primary determinant of the efficacy of renal OA transport and elimination. Finally, expression cloning and PCR probes have been utilized to screen a CDNA library prepared from rat kidney mRNA for the genes coding for these two important excretory transport systems. We have identified a clone for a pH-driven, potential-sensitive OC carrier. It is now being sequenced. A positive signal is also present in our library for an OA transporter and screening is under way to isolate it as well.