SPECTRAL AND METABOLIC BASIS OF VISUAL RESPONSES

这项应用提出了研究光和光的过程的实验 离体脊椎动物的暗适应和氧化代谢 光感受器。这些细胞在背景和背景下的电响应 使用吸力微电极将获得适合漂白剂的条件。 视觉色素含量的变化将使用 显微分光光度法。分离的细胞的氧化代谢将是 使用微型氧气敏感电极进行测量。 心理物理学已经表明，背景和漂白适应是 “等同”。这一规则的例外情况主要涉及 使用时变刺激的脱敏，这可能是由于非 光感受器反应动力学的等价性。我们建议比较一下 杆和锥体在同等背景和水平下的响应动力学 漂白适应。 视杆细胞和视锥细胞外段内钙水平[Ca~(2+)]i 最近被证明可以调节背景适应。我们建议 研究[Ca~(2+)]i是否也是漂白适应的中介。 从漂白适应中恢复需要再生视觉色素， 但使用11顺式锁定的视网膜类似物，我们发现它不是 需要形成一种转导的视觉色素。我们建议使用其他 视网膜类似物以研究恢复是否需要形成 视素-生色团席夫碱，或简单地占据发色团 结合部位。 光明和黑暗期间视觉色素水平的维持和恢复 适应需要视黄醇在视网膜和色素之间移动 上皮细胞，可能涉及IRBP(光感受器间类维甲酸结合 蛋白质)。我们已经能够将维甲酸从IRBP转移到孤立的 光感受器(促进暗适应)。我们建议调查 进一步这种转移，特别是视黄醇和视黄醇的转移 视网膜到光感受器，并研究IRBP在 光适应过程中类维甲酸的转移，即从 光感受器。 以前对光感受器耗氧量的解释是 由于测量不是单独进行的而受到阻碍。 研究单个感光细胞的耗氧量应 删除此问题。我们将调查氧气消耗是否 由光触发，以及它是否由能级的变化控制 [Na+]i或[Ca2+]i。

This application proposes experiments to study the processes of light and dark adaptation as well as oxidative metabolism in isolated vertebrate photoreceptors. Electrical responses of these cells under background and bleach-adapted conditions will be obtained using suction microelectrodes. Changes in visual pigment content will be measured using microspectrophotometry. Oxidative metabolism of isolated cells will be measured using miniature oxygen-sensitive electrodes. Psychophysics has shown that background and bleaching adaptation are "equivalent". Exceptions to this rule involve principally measures of desensitization using time varying stimuli, that could be due to non- equivalence in photoreceptor response kinetics. We propose to compare response kinetics of rods and cones at equivalent levels of background and bleaching adaptation. The internal calcium level [Ca2+]i in rod and cone outer segments has recently been shown to regulate background adaptation. We propose to investigate whether [Ca2+]i is also a mediator of bleaching adaptation. Recovery from bleaching adaptation requires regeneration of visual pigment, but using 11-cis locked retinal analogs, we have found that it does not require formation of a transducing visual pigment. We proposed using other retinal analogues to investigate whether recovery requires formation of an opsin-chromophore Schiff base, or simply occupation of the chromophore binding site. Maintenance and restoration of visual pigment levels during light and dark adaptation requires movement of retinoid between retina and pigment epithelium and likely involves IRBP (interphotoreceptor retinoid-binding protein). We have been able to transfer retinoid from IRBP to isolated photoreceptors (promoting dark adaptation). We propose to investigate further this transfer, in particular the transfer of both retinol and retinal to photoreceptors, and also to investigate the role of IRBP in the transfer of retinoid during light adaptation, i.e. transfer from photoreceptors. Previous interpretations of the O2 consumption of photoreceptors have been hampered by the measurements not having been made in isolation. Investigation of the O2 consumption of single photoreceptor cells should remove this problem. WE will investigate whether the O2 consumption is triggered by light, and whether it is controlled by changes in the levels of [Na+]i or [Ca2+]i.