ELECTROCHEMICAL SIGNALING IN VERTEBRATE PHOTORECEPTORS

脊椎动物光感受器中的电化学信号传导

• 批准号: 3264008
• 负责人: JOHN W MOORE
• 金额: $ 19.89万
• 依托单位: DUKE UNIVERSITY
• 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 1989-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3264008
• 关键词: adenylate cyclase; calcium; cone cell; cyclic GMP; dark adaptation; electrochemistry; fresh water environment; guanylate cyclase; light adaptations; phosphodiesterases; rhodopsin; rod cell; visual photoreceptor; visual photosensitivity

The long term objective is to understand the detailed mechanisms involved in transduction and light adaptation in vertebrate photoreceptors. The results may help our understanding of dysfunction of photoreceptors and other, related second messenger systems. It is known that the electrical response to light in vertebrate photoreceptors results from closure of light-sensitive Na channels. These channels are held open by cGMP in the dark, and close in light because a light-activated phosphodiesterase rapidly hydrolyses cGMP and so reduces its concentration. The phosphodiesterase is activated by rhodopsin via an intermediate G-protein, transducin. However, details of the biochemical steps and their control by ions such as Ca are poorly understood. Little is known about the corresponding biochemical processes in cones. One immediate aim is to determine whether the form of the light response in rods and cones can be accounted for by changes in the activities of the cyclase and the phosphodiesterase. The activities of the cyclase and phosphodiesterase will be determined indirectly from rapid solution substitution experiments. A second aim is to determine the origin of noise processes in rods and cones. A major goal is to investigate the biochemical pathway in single rods and cones by introducing chemicals or proteins into single photoreceptors using whole-cell patch electrodes. Similar techniques will be used to examine the relationship between proteins involved in phototransduction and those in other G- protein systems such as the hormone-activated adenylate cyclase system. The light-sensitive current will usually be measured using a suction electrode and external solutions will be changed using either rapid flow methods or internal perfusion of the suction electrode.

长期目标是了解详细的机制 参与脊椎动物的信号转导和光适应 光感受器 这些结果可能有助于我们了解 光感受器和其他相关功能障碍 信使系统 已知脊椎动物对光的电反应 光感受器的结果关闭光敏钠 渠道 这些通道在黑暗中由cGMP保持开放， 因为光激活的磷酸二酯酶迅速 水解cGMP，从而降低其浓度。 的 磷酸二酯酶被视紫红质通过中间体激活 G蛋白，转导蛋白。 然而，生化步骤的细节 并且它们受离子如Ca的控制知之甚少。 小 我们已经了解了锥细胞中相应的生化过程。 一个直接的目标是确定光的形式 视杆细胞和视锥细胞中的反应可以通过 环化酶和磷酸二酯酶的活性。 的 将测定环化酶和磷酸二酯酶的活性 快速溶液替代实验。 第二 目的是确定棒中噪声过程的起源， 圆锥体。 一个主要的目标是研究生物化学途径， 通过引入化学物质或蛋白质， 使用全细胞贴片电极的单个光感受器。 类似 技术将被用来检查之间的关系， 参与光传导的蛋白质和其他G- 蛋白质系统，如腺苷酸环化酶 系统 光敏电流通常使用 将使用以下方法更换吸引电极和外部溶液 快速流动方法或抽吸的内部灌注 电极上