CORNEAL ARACHIDONATE METABOLITES VIA CYTOCHROME P450

通过细胞色素 P450 测定角膜花生四烯酸代谢物

• 批准号: 3262758
• 负责人: Michal Laniado Schwartzman
• 金额: $ 10.17万
• 依托单位: NEW YORK MEDICAL COLLEGE
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-08-01 至 1990-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3262758
• 关键词: NADPH cytochrome c2 reductase; adenosinetriphosphatase; antibody; arachidonate; autoradiography; chemical structure; cornea; cytochrome P450; eicosanoid metabolism; enzyme inhibitors; epithelium; gas chromatography mass spectrometry; high performance liquid chromatography; intraocular pressure; isozymes; laboratory rabbit; laboratory rat; lens; liposomes; lipoxygenase; membrane transport proteins; prostaglandin endoperoxide synthase; retinal pigment epithelium; sodium potassium exchanging ATPase; tissue /cell culture; uvea ciliary body; vascular endothelium; vascular resistance

The epithelial cell layers of the cornea can be characterized as a "tight" ion transporting functional syncytium which serves both as a protective barrier to the ocular surface, and as an adjunct fluid- secreting layer assisting the corneal endothelium in the regulation of stromal hydration and, thereby, contributing to the maintenance of corneal transparency. Transport properties of the corneal epithelium are similar to those of the epithelial cells of the thick ascending limb of Henle's loop (TALH), the nephron segment that is important for establishing the solute gradient for urinary concentration through sodium chloride coupled transport. Both transport epithelia possess active chloride transport coupled to Na+-K+-activated ATPase. Recently, we reported that cells of the TALH metabolized arachidonic acid (AA) by cytochrome P450-dependent enzyme(s) to two biologically active metabolites: one inhibits Na+-K+-ATPase and the other relaxes blood vessels. The observations that prostaglandins and other AA oxygenated metabolites may act as a mediator(s) of transport process, and the similarity of the corneal epithelium to TALH as regards ion transport mechanism, led us to investigate the possibility that the cytochrome P450-dependent AA metabolism exists in the corneal epithelium. Our preliminary results demonstrate for the first time that the epithelium of the cornea contains a cytochrome P450 species capable of metabolizing AA to several compounds. Exactly what these compounds are and whether they have biological effects on cell function and ion transport are questions which will be addressed in this study. We expect, based on parallel studies in the TALH of the kidney, that our work will reveal substances which affect Na+-K+-ATPase activity and vascular reactivity. Indeed, in a recent experiment we demonstrated the ability of one of the corneal AA metabolites to inhibit Na+-K+-ATPase of the cornea. Such an endogenous inhibitor of Na+-K+-ATPase synthesized in the cornea may have fundamental importance in ocular transport epithelia that rely on this pump mechanism. These include the corneal epithelium and endothelium, the epithelia of the ciliary body, the lens subcapsular epithelium and the retinal pigment epithelium. Furthermore, the identification of an endogenous substance which promotes vasodilatation may have significance in diverse areas of physiology and pathophysiology such as inflammatory mechanisms, control of the ocular circulation and aqueous humor dynamics.

角膜的上皮细胞层可以表征为 “紧密”离子运输功能合胞体，既充当 眼表的保护屏障，并作为辅助液体- 分泌层协助角膜内皮调节 基质水合作用，从而有助于 维持角膜透明度。 的运输特性 角膜上皮与角膜上皮细胞相似 亨利袢粗升肢 (TALH)，肾单位 对于建立溶质梯度很重要的部分 通过氯化钠耦合运输进行尿液浓缩。 两种运输上皮都具有活性氯离子运输耦合 至 Na+-K+ 激活的 ATP 酶。 最近，我们报道了细胞 TALH 通过细胞色素代谢花生四烯酸 (AA) 两种生物活性代谢物的 P450 依赖性酶： 一种抑制Na+-K+-ATP酶，另一种舒张血管。 前列腺素和其他 AA 氧化的观察结果 代谢物可以充当运输过程的介质，并且 角膜上皮与 TALH 在离子方面的相似性 运输机制，使我们研究了这种可能性 角膜中存在细胞色素 P450 依赖性 AA 代谢 上皮。 我们的初步结果首次表明 角膜上皮含有细胞色素 P450 种类 能够将AA代谢成多种化合物。 到底是什么 这些化合物是否具有生物效应 细胞功能和离子运输是需要解决的问题 本研究中提出。 我们预计，基于平行研究 肾脏的 TALH，我们的工作将揭示物质 影响Na+-K+-ATP酶活性和血管反应性。 事实上，在最近的一项实验中，我们展示了一种能力 角膜 AA 代谢物抑制 Na+-K+-ATPase 角膜。 这种 Na+-K+-ATPase 内源性抑制剂 在角膜中合成可能具有根本重要性 依赖这种泵机制的眼部运输上皮细胞。 这些包括角膜上皮和内皮， 睫状体上皮、晶状体囊下上皮和 视网膜色素上皮。 此外，鉴定 促进血管舒张的内源性物质可能 在生理学的各个领域都具有重要意义 病理生理学，例如炎症机制、控制 眼循环和房水动力学。