Control of motility in the internal anal sphincter

 描述(申请人提供)：肛门内括约肌(IAS)负责约70%的肛门静息张力，这一作用对维持可控性至关重要。IAS的收缩调节机制与大肠的其他区域有显著不同，在其他区域，肠腔内容物的混合和向前推进占主导地位。前人对IAS的研究主要集中在使肌丝对细胞内钙离子浓度([Ca]i)敏感的机制上，但如果没有电压依赖性钙通道(VDCC)持续的钙离子进入细胞内，IAS就不可能有张力。同样，任何减少VDCC活动的过程(如神经活动)都会降低音调。我们在过去融资期间的发现导致了这样的假设，即慢波(Sw)在维持IAS的语调方面发挥着基础性作用。在下一个资助阶段，我们将研究ICC和另一种间质细胞类型“PDGFRA+细胞”在短波的产生和IAS的抑制性神经肌肉传递(NMT)中的作用。我们将使用一些新开发的转基因小鼠，在这些小鼠中，特定类别的细胞表达各种荧光标记或钙离子指示剂，或关键基因失活。钙离子成像研究将确定Sw起源的部位，并发现哪些细胞对抑制性运动神经支配有反应。还将收集特定的细胞群体用于分子分析和膜片钳研究。如果可能，我们还将把这些结果应用于食蟹猴IAS的平行研究，食蟹猴是人类的近亲。IAS的功能失调导致严重的社会孤立、失业和制度化，并使美国的医疗保健系统每年损失数十亿美元。尽管有如此巨大的卫生保健负担，IAS仍是胃肠道中研究最少的区域。这一建议将把免疫荧光技术的研究带入细胞分子探针、转基因技术和严谨的机制研究的现代时代。这些信息可能会为治疗涉及不适当IAS语气的排便障碍提供新的理论依据。

 DESCRIPTION (provided by applicant): The internal anal sphincter (IAS) is responsible for ~70% of anal resting tone, a role that is critical for maintaining continence. Mechanisms regulating contraction in the IAS differ significantly from other regions of the large intestine where mixing and the forward propulsion of luminal contents predominate. Studies of the IAS by others have focused on mechanisms that sensitize the myofilaments to intracellular Ca2+concentration ([Ca]i) but without the continued entry of calcium into cells through voltage dependent calcium channels (VDCC) there can be no tone in the IAS. Likewise, any process (such as neural activity) that reduces VDCC activity will reduce tone. Our findings during the past funding period have led to the hypothesis that slow waves (SW) play a fundamental role in maintaining tone in the IAS. In the next funding period we examine the role ICC and a second interstitial cell type referred to as "PDGFRa+ cells" in the generation of SW and in inhibitory neuromuscular transmission (NMT) in the IAS. We will use a number of newly developed transgenic mice in which specific classes of cells express various fluorescent tags or Ca2+ indicators or have key genes deactivated. Ca2+ imaging studies will identify sites of SW origin and discover which cells respond to inhibitory motor innervation. Specific cell populations will also be collected for molecular analyses and patch clamp studies. When possible we will also apply these results to parallel studies of IAS from Cynomolgus monkeys, a close genetic relative of humans. Dysfunction of the IAS leads to substantial social isolation, loss of employment, and institutionalization as well as costing the health care system in the USA billions of dollars annually. In spite of this large health care burden the IAS is the least studied region of the GI tract. This proposal will bring studies of the IAS into the modern era of cellular molecular probes transgenic technology and rigorous investigation of mechanism. Such information is likely to provide novel rationales for treating defecation disorders involving inappropriate IAS tone.