Intraocular pressure regulation via ATP-sensitive potassium channels

描述（由申请人提供）：这是一项研究通过三磷酸腺苷敏感性钾（KATP）通道调节眼内压（IOP）的分子事件的申请。眼压升高是青光眼唯一可治疗的风险因素。不幸的是，涉及外流阻力和IOP控制的关键分子是未知的。缺乏这方面的知识，限制了药物的发展，将这些过程的目标。我们最近发现了一个关键的细胞效应的IOP，可能导致新的药物治疗高眼压症和青光眼。我们发现，在人眼前节灌注模型中，KATP通道开放剂二氮嗪、尼可地尔和P-1075激活KATP通道可降低IOP。药物开放剂对KATP通道的激活可被KATP通道关闭剂格列本脲和甲苯磺丁脲阻断。此外，KATP通道开放剂二氮嗪和前列腺素类似物拉坦前列素治疗增加的流出道灵活性大于单独使用任何一种药物，表明这些药物使用不同的机制来降低IOP。到目前为止，还没有涉及KATP通道的研究已经进行了小梁流出途径。KATP通道的打开和关闭已显示改变细胞收缩性和渗透性，提供针对缺血和缺氧的代谢保护，并增强非眼组织中细胞对应激的适应。所有这些细胞事件都直接或间接地与青光眼的原因有关。我们认为，为了开发用于治疗IOP升高的药理学药物，我们必须首先确定参与降低IOP的关键内在分子和生理机制。我们的中心假设是KATP通道激活引起的细胞事件导致IOP降低。我们的前提是，KATP通道激活导致小梁网松弛，从而导致渗透性增加、液体流动改善、流出功能增强和IOP降低。我们建议表征KATP通道亚基结构，识别由KATP通道开放剂激活的细胞通路，并确定将KATP通道开放与增加的流出设施和通过小梁流出通路降低IOP偶联的生理功能。此外，我们将确定KATP通道开放剂对正常眼和原发性开角型青光眼（POAG）眼IOP的影响。在体内，我们将分析KATP通道开放剂及其对C57 BL/6野生型和特异性KATP通道亚基敲除小鼠IOP的影响。本提案的完成将提供对KATP通道在小梁流出通路中的作用的完整描述性和机制性理解，并将有助于评估使用KATP通道开放剂作为增加POAG流出功能的治疗方式的可行性。 公共卫生相关性：对KATP通道的拟议研究将产生关于用于降低正常和POAG眼中IOP的机制的新信息。分析KATP通道亚基结构和确定受KATP通道开放剂影响的细胞途径将确定未来治疗可针对的新靶分子。更重要的是，KATP通道开放剂的分析可能导致一类新的药物用于治疗高眼压症和青光眼。

DESCRIPTION (provided by applicant): This is an application to study the molecular events involved in intraocular pressure (IOP) regulation through adenosine-triphosphate-sensitive potassium (KATP) channels. Elevated IOP is the only treatable risk-factor for glaucoma. Unfortunately, the key molecules involved in outflow resistance and IOP control are unknown. Lack of this knowledge has limited the development of pharmacologic agents that would target these processes. We recently identified a key cellular effector of IOP that may lead to new pharmacologic treatment for ocular hypertension and glaucoma. We have found that activation of KATP channels by KATP channel openers diazoxide, nicorandil, and P-1075 lower IOP in a human anterior segment perfusion model. This activation of KATP channels by the pharmacologic openers can be blocked by KATP channel closers, glyburide, and tolbutamide. In addition, treatment with the KATP channel opener diazoxide and the prostaglandin analogue latanoprost increases outflow facility greater than either agent does individually, suggesting that these agents use distinct mechanisms to lower IOP. To date, no studies involving KATP channels have been performed in the trabecular outflow pathway. The opening and closing of KATP channels have been shown to alter cellular contractility and permeability, provide metabolic protection against ischemia and hypoxia, and enhance cellular adaptation to stress in non-ocular tissues. All of these cellular events have been directly or indirectly linked to the cause of glaucoma. We believe that in order to develop pharmacologic agents for the treatment of elevated IOP, we must first identify key intrinsic molecules and physiological mechanisms involved in lowering IOP. Our central hypothesis is that cellular events resulting from KATP channel activation leads to IOP reduction. It is our premise that KATP channel activation leads to a relaxation of the trabecular meshwork resulting in increased permeability, improved fluid flow, augmented outflow facility, and a decrease in IOP. We propose to characterize KATP channel subunit structure, identify cellular pathways activated by KATP channel openers, and determine the physiological function that couples KATP channel opening to increased outflow facility and a lowering of IOP through the trabecular outflow pathway. In addition, we will determine the effect of KATP channel openers on IOP in normal and primary open-angle glaucoma (POAG) eyes. In vivo, we will analyze KATP channel openers and its effect on IOP in C57BL/6 wild-type and specific KATP channel subunit knockout mice. The completion of this proposal will provide a complete descriptive and mechanistic understanding of the role KATP channels have in the trabecular outflow pathway, and will help in evaluating the feasibility of using KATP channel openers as a treatment modality for increasing outflow facility in POAG. PUBLIC HEALTH RELEVANCE: The proposed studies on KATP channels will yield novel information regarding the mechanisms used to lower IOP in normal and POAG eyes. Analysis of KATP channel subunit structure and determination of cellular pathways affected by KATP channel openers will identify novel target molecules to which future therapies can be directed. More importantly, the analysis of KATP channel openers may result in a new class of drugs for the treatment of ocular hypertension and glaucoma.