Cellular electrophsyiology of vasculatures in the inner ear

描述（由申请人提供）：血液循环障碍可导致听力损失，包括耳鸣引起的创伤、衰老、梅尼埃病、耳毒性药物和某些形式的突发性耳聋。内耳血管生理学的知识是理解和治疗这些听力疾病的基础，但该领域的探索仍然很少。该实验室的长期目标是确定耳蜗血管的常见和独特的病理生理机制，负责耳蜗血流调节的关键神经体液信使，受体和通道，并发现预防和治疗这些听力损失的药物。我们前期的研究发现耳蜗螺旋蜗轴动脉（SMA）在静息膜电位（RP）调节和神经肌肉传递中具有独特的血管张力控制机制。基于这些发现，本提案设定了以下目标：1）确定SMA细胞的双峰RP分布的机制和意义以及缺血/再灌注引起RP分布和血管紧张素反应变化的机制; 2）确定介导候选神经递质（例如，去甲肾上腺素、乙酰胆碱、CGRP）; 3）鉴定候选神经递质在SMA中的内在神经肌肉传递中的作用。这些目标将通过使用常规和全细胞电流和电压钳记录方法对体外血管平滑肌细胞（VSMC）进行实验，加上多种方法，如计算建模，血管直径跟踪，一氧化氮产生监测，免疫细胞化学，RT-PCR和Western印迹分析来实现。通过这些研究，我们期望发现关键通道蛋白Kir与其他持续性膜电流，如KATP和Na+K+泵电流共同作用，产生双峰RP，从而实现耳蜗血流的高自动调节能力。我们还预计，缺血/再灌注治疗将导致一氧化氮的产生，KATP和Kir的表达上调，从而导致RP的人口移动和血管反应性的变化。新的神经肌肉传递和各种药物作用的特点。所获得的知识将提高我们对耳蜗血流如何调节以及导致耳蜗循环不足的关键因素的理解，从而有助于更好地预防和治疗循环相关的听力损失，甚至心脏病发作和中风。所获得的知识应该提高我们对耳蜗血流如何独特调节的理解，从而有助于理解与循环相关的听力损失，并导致这些听力状况的预防和治疗。所获得的知识也应该在心血管生理学和心血管疾病病理生理学的广泛领域具有重要意义。

DESCRIPTION (provided by applicant): Blood circulation disturbances contribute to the hearing loss in loud-sound induced trauma, aging, Meniere's disease, ototoxic drugs and some forms of sudden deafness. Knowledge of inner ear vascular physiology is fundamental to understanding and treating these hearing conditions, but the field remains poorly explored. The long-term goal of this lab is to determine the common and unique patho-physiological mechanisms of cochlear vessels, the key neurohumoral messengers, receptors and channels responsible for cochlear blood flow regulation, and to discover drugs for prevention and treatment of these hearing losses. Our previous studies have found that the cochlear spiral modiolar artery (SMA) has unique vascular tone control mechanisms in resting membrane potential (RP) regulation and neuromuscular transmission. Based on these findings, this proposal sets the following aims: 1) to determine the mechanism and significance that underlie the bi-modal RP distribution of the SMA cells and the mechanism by which ischemia/reperfusion causes the change of the RP distribution and vasotone response; 2) to determine the ion channel(s) and receptor type(s) that mediate the actions of the candidate neurotransmitters (e.g., norepinephrine, acetylcholine, CGRP); 3) to identify the role of candidate neurotransmitters in intrinsic neuromuscular transmission in the SMA. These goals will be achieved through experiments using conventional and whole-cell current- and voltage-clamp recording methods on the in vitro vascular smooth muscle cells (VSMC), plus multiple approaches such as computational modeling, vaso-diameter tracking, nitric oxide production-monitoring, immunocytochemistry, RT-PCR and Western blot analyses. With these studies, we expect to find that the Key channel protein, Kir, co-plays with other persistent membrane currents, such as KATP and Na+K+pump currents, to generate the bimodal RP and thus to achieve a high autoregulation capacity of cochlear blood flow. We also anticipate that ischemia/reperfusion treatment will cause up-regulation of nitric oxide production, KATP and Kir expression, and thus cause the RP population shift and the vascular responsiveness change. The novel neuromuscular transmission and various drug effects will be characterized. The knowledge obtained will improve our understanding of how cochlear blood flow is regulated and what are the key factors causing cochlear circulation-deficiency, thus contributing to better prevention and treatment of the circulation-implicated hearing loss, and even the heart attack & stroke. The knowledge obtained should improve our understanding of how cochlear blood flow is uniquely regulated, thus contributing to understanding of circulation-related hearing losses and leading to prevention and treatment of these hearing conditions. The acquired knowledge should also be of significance in broad areas of cardiovascular physiology, and cardiovascular disease pathophysiology.