Nerve Evoked Signaling in Urinary Bladder Smooth Muscle

描述(申请人提供)：膀胱平滑肌(UBSM)的中心功能是将神经输入转化为正常的排尿反应，这种功能随着出口梗阻而显著改变。本研究的重点是这些通过胆碱能和嘌呤能通路的神经输入如何不同地影响UBSM中的钙(Ca~(2+))信号模式，以及在正常情况下和部分出口梗阻时对电和收缩反应的影响。尽管这些途径很重要，但我们对潜在的神经诱发兴奋-收缩(E-C)耦合机制和梗阻所发生的变化的了解仍然存在重大差距。在一个重大进展中，我们已经能够以高空间和时间分辨率测量完整的完整膀胱和膀胱条中的神经兴奋和局部钙信号。我们在UBSM中发现了两个不同的局部钙瞬变：1)神经诱发的钙瞬变，通过嘌呤能受体介导；2)通过兰尼定受体(RyRs)从肌浆网(SR)局部释放钙。目的1阐明UBSM通过电压依赖性钙通道(VDCC)、三磷酸肌醇受体(IP3Rs)和SR中的RyRs将胆碱能和嘌呤能信号解码为不同的钙信号的新机制。目的2重点研究UBSM的E-C偶联机制，以响应胆碱能和嘌呤能机制所引发的独特的钙信号。在目标3中，我们探讨了VDCC和SR钙负荷在介导正常和功能障碍膀胱的胆碱能和嘌呤能兴奋中的相互作用。出口梗阻后SR功能障碍通过改变UBSM钙信号而不同地影响胆碱能和嘌呤能刺激的假说将得到验证。利用最先进的技术、转基因小鼠和我们最近开发的部分膀胱出口梗阻小鼠模型，拟议的研究将为正常和梗阻膀胱中胆碱能和嘌呤能通路对UBSM的不同影响提供新的见解。这项研究的新发现将与了解UBSM神经诱发的E-C偶联的基本机制高度相关，并找出导致膀胱功能障碍的关键因素，因此应该与理解和治疗膀胱功能障碍高度相关。

DESCRIPTION (provided by applicant): A central function of urinary bladder smooth muscle (UBSM) is the translation of neural inputs into a normal micturition response, a function that is dramatically altered with outlet obstruction. This proposal focuses on how these neural inputs through cholinergic and purinergic pathways differentially impact calcium (Ca2+) signal patterning in UBSM, and on electrical and contractile responses under normal conditions and with partial outlet obstruction. Despite the importance of these pathways, major gaps remain in our knowledge o1 the underlying nerve-evoked excitation-contraction (E-C) coupling mechanisms and the changes that occur with obstruction. In a major advance, we have been able to measure, with high spatial and temporal resolution, nerve excitation, and local Ca2+ signals in intact whole urinary bladders and bladder strips. We have identified two distinct local calcium transients in UBSM: 1) nerve-evoked calcium transients, mediated through purinergic receptors, and 2) the local release of calcium from the sarcoplasmic reticulum (SR) through ryanodine receptors (RyRs). Aim 1 seeks to elucidate the novel mechanisms by which UBSM decodes cholinergic and purinergic stimulation into different calcium signals, which differentially depend on Ca2+ entry through voltage-dependent calcium channels (VDCC), inositol triphosphate receptors (IP3Rs) and RyRs in the SR. Aim 2 focuses on UBSM E-C coupling mechanisms in response to the unique calcium signals elicited by cholinergic and purinergic mechanisms. In Aim 3, we explore the interaction of VDCC and SR Ca2+ load in mediating cholinergic and purinergic excitation in normal and dysfunctional bladders. The hypothesis that SR dysfunction following outlet obstruction differentially affects cholinergic and purinergic stimulation by altered UBSM calcium signaling will be tested. Using state-of-the-art techniques, genetically altered mice, and our recently developed mouse model of partial bladder outlet obstruction, the proposed study will provide new insights into the differential impact of cholinergic and purinergic pathways on UBSM in normal and obstructed bladders. The novel findings of this study will be highly relevant to understanding fundamental mechanisms of nerve-evoked E-C coupling in UBSM, and identify key elements that underlie bladder dysfunction, and as such should be highly relevant to the understanding and treatment of bladder dysfunction.