Cellular electrophsyiology of vasculatures in the inner ear

描述(申请人提供)：血液循环障碍导致听力损失的大声音创伤，衰老，梅尼埃病，耳毒性药物和一些形式的突发性耳聋。内耳血管生理学知识是了解和治疗这些听力疾病的基础，但该领域的探索仍然很少。本实验室的长期目标是确定耳蜗血管的共同和独特的病理生理机制，耳蜗血管是负责耳蜗血流量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。我们以前的研究发现，耳蜗螺旋动脉(SMA)在静息膜电位(RP)调节和神经肌肉传递方面具有独特的血管张力控制机制。基于这些发现，本研究确定了以下目标：1)确定SMA细胞双模式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改变的机制；2)确定介导候选神经递质(如去甲肾上腺素、乙酰胆碱、降钙素基因相关肽)作用的离子通道(S)和受体类型(S)；3)确定候选神经递质在SMA内源性神经肌肉传递中的作用。这些目标将通过在体外血管平滑肌细胞(VSMC)上使用传统的和全细胞电流和电压钳记录方法，加上计算建模、血管直径跟踪、一氧化氮产生监测、免疫细胞化学、RT-PCR和Western印迹分析等多种方法来实现。通过这些研究，我们有望发现关键的通道蛋白KIR与其他持续的膜电流，如KATP和Na+K+泵电流，共同作用产生双峰RP，从而实现对耳蜗血流量的高自动调节能力。我们还预计，缺血/再灌注处理将导致一氧化氮的产生、KATP和KIR的表达上调，从而导致RP群体移动和血管反应性改变。新的神经肌肉传递和各种药物作用将被描述。这些知识将加深我们对耳蜗血流量是如何调节的，以及导致耳蜗血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性听力损失，甚至心脏病发作和中风。所获得的知识应该会提高我们对耳蜗血流量是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，并导致这些听力疾病的预防和治疗。所获得的知识在心血管生理学和心血管疾病病理生理学的广泛领域也应该具有重要意义。

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.