COUPLING BETWEEN METABOLISM/IONIC TRANSPORT IN CORNEAS

角膜代谢/离子运输之间的耦合

• 批准号: 3259316
• 负责人: Peter S Reinach
• 金额: $ 7.69万
• 依托单位: AUGUSTA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-07-01 至 1991-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3259316
• 关键词: Anura; adrenergic agents; calcium transporting ATPase; calmodulin; cell morphology; corneal epithelium; cyclic AMP; drug metabolism; electrophysiology; eye pharmacology; freeze etching; fresh water environment; homeostasis; ionophores; laboratory rabbit; membrane permeability; membrane structure; membrane transport proteins; microelectrodes; osmosis; phosphatidylinositols; protein kinase C; second messengers; sodium potassium exchanging ATPase; stoichiometry

In the isolated amphibian and mammalian cornea, the maintenance of corneal transparency and deturgescence is in part dependent on the rate of net transepithelial Cl transport. Two potent classes of stimulators of this transport process are cyclic AMP mediating agents and the Ca ionophores. These effects coupled with the characterization of high affinity Ca stimulated Mg dependent ATPase/Ca pump activities are part of the basis for suggesting that changes in intracellular cyclic AMP content and Ca activity both serve a second messenger function in eliciting stimulus-secretion coupling. The overall aim is to continue our characterization in the mammalian and amphibian corneal epithelium of the interrelationships and interdependencies among changes in intracellular cyclic AMP content and Ca activities in their possible control of various cell functions. The approaches to this problem are biochemical and electrophysiological in nature. The biochemical approach is at the cellular and subcellular level and its purpose is to obtain insight about: (1) How intracellular Ca activity is maintained at submicromolar levels, which is a requirement for Ca to have a second messenger function; (2) Which metabolic pathways are sensitive to changes in intracellular Ca as well as the mechanism whereby this second messenger exerts its regulatory effects on these pathways; and (3) Any interrelationships and interdependencies among changes in cyclic AMP and Ca levels in mediating their control over these pathways. The electrophysiological approach is concerned with the characterization of the mechanisms of regulation of transepithelial net ion transport. With this approach, it is possible to determine: (1) Which membrane parameters are affected by changes in intracellular cyclic AMP and Ca levels; (2) The stoichiometry of Na:K pumps and symports: (3) Putative cell volume changes in response to alteration of bathing solution tonicity, and (4) If there is a relationship among cell-to-cell coupling and changes in intracellular Ca and pH.

在孤立的两栖动物和哺乳动物角膜中，角膜维护 透明度和破坏性部分取决于净率 transepithepithial cl运输。 这两个有效的刺激剂 运输过程是环状AMP介导剂和CA离子载体。 这些效果以及高亲和力CA的表征 受刺激依赖的MG ATPase/CA泵活动是基础的一部分 表明细胞内环状AMP含量和CA活性的变化 两者都在引发刺激 - 分泌方面发挥第二个信使功能 耦合。 总体目的是继续我们的表征 相互关系的哺乳动物和两栖动物角膜上皮 细胞内循环AMP含量和CA的变化之间的相互依存关系 它们可能控制各种细胞功能的活动。 这 解决这个问题的方法是生化和电生理学 自然。 生化方法在细胞和亚细胞水平 它的目的是获得有关：（1）细胞内CA的见解 活动保持在亚旋风水平，这是对 CA具有第二个Messenger功能； （2）哪种代谢途径是 对细胞内CA的变化以及机制敏感 第二个使者对这些途径施加了调节作用。和 （3）循环变化之间的任何相互关系和相互依存关系 放大器和CA水平介导了它们对这些途径的控制。 这 电生理方法与表征有关 调节跨越净离子运输的机制。 与此 方法，可以确定：（1）哪些膜参数为 受细胞内循环AMP和CA水平的变化的影响； （2） Na：K泵和交易的化学计量法：（3）推定的细胞体积变化 响应沐浴溶液的改变，以及（4）如果有 细胞间耦合与细胞内CA的变化之间的关系 和ph。