Chloride Cotransporter Function in the Retina

描述（由申请人提供）：本研究项目是一项实验研究，旨在了解阳离子氯协同转运蛋白在视网膜信息处理中的作用。在视网膜和中枢神经系统的其他地方，已经确定了两种类型的氯化物协同转运蛋白：Na-K-2Cl（NKCC）和K-Cl（KCC）协同转运蛋白。这些氯离子协同转运蛋白调节细胞内氯离子浓度，使得KCC从神经元中挤出氯离子，而NKCC将氯离子转运到细胞中。因此，当氯平衡电位由于KCC的作用而比静息膜电位更负时，打开氯通道的神经递质GABA使神经元超极化。相反，当氯平衡电位比静息膜电位更正时，由于NKCC的作用，GABA使神经元去极化。因此，根据视网膜神经元表达的氯离子协同转运蛋白的类型，GABA会使细胞过度兴奋或去兴奋。因此，我们将确定氯离子协同转运蛋白在视网膜中的作用，通过使用电生理学，神经化学，细胞/分子和解剖技术的组合。本实验将利用兔眼杯神经视网膜标本研究氯离子协同转运蛋白在视网膜外层的方向选择性和突触传递中的作用。具体地说，我们将确定在光适应条件下，氯协同转运蛋白活性是否介导双极细胞和神经节细胞周围的感受野。我们还将确定的作用的氯cotorporters在定向选择性的光反应的星爆无长突细胞，interneurons是突触前开-关定向选择性神经节细胞。公共卫生相关性：对成人视网膜中氯离子协同转运蛋白活性的了解将有助于了解人类视网膜功能和功能障碍，并为涉及氯离子协同转运蛋白的视网膜疾病（如视网膜缺血）的药物治疗提供基础。此外，增加氯协同转运蛋白的知识可能有助于理解和治疗癫痫和其他涉及氯稳态和GABA的疾病。

DESCRIPTION (provided by applicant): This research project is an experimental study that seeks to understand the role of cation-chloride cotransporters in information processing in the retina. In the retina and elsewhere in the central nervous system, two types of chloride cotransporter, the Na-K-2Cl (NKCC) and K-Cl (KCC) cotransporters, have been identified. These chloride cotransporters regulate the intracellular chloride concentration such that KCC extrudes chloride from neurons, whereas NKCC transports chloride into cells. Thus, the neurotransmitter GABA, which opens chloride channels, hyperpolarizes neurons when the chloride equilibrium potential is more negative than the resting membrane potential due to the action of KCC. In contrast, GABA depolarizes neurons when the chloride equilibrium potential is more positive than the resting membrane potential due to the action of NKCC. Thus, depending on the type of chloride cotransporter expressed by a retinal neuron, GABA will either hyperpolarize or depolarize the cell. We will therefore determine the roles of chloride cotransporters in the retina by using a combination of electrophysiological, neurochemical, cell/molecular and anatomical techniques. The rabbit eyecup neural retina preparation will be used to study the roles of chloride cotransporters in directional selectivity and in synaptic transmission in the outer retina. Specifically, we will determine whether chloride cotransporter activity mediates the receptive field surround of bipolar cells and ganglion cells under light- adapted conditions. We will also determine the roles of the chloride cotransporters in the directionally selective light responses of starburst amacrine cells, interneurons that are pre-synaptic to ON-OFF directionally selective ganglion cells. PUBLIC HEALTH RELEVANCE: Increased knowledge of chloride cotransporter activity in the adult retina will aid in the understanding of human retinal function and dysfunction, as well as provide the basis for drug therapy for retinal disorders, such as retinal ischemia, that involve the chloride cotransporters. In addition, increased knowledge of chloride cotransporters may aid in the understanding and treatment of epilepsy and other diseases that involve chloride homeostasis and GABA.