Control of motility in the internal anal sphincter

 描述（由申请人提供）：肛门内括约肌（IAS）负责约70%的肛门静息张力，这是维持肛门张力的关键作用。调节IAS收缩的机制与大肠的其他区域显著不同，在这些区域中管腔内容物的混合和向前推进占主导地位。其他人对IAS的研究集中在使肌丝对细胞内Ca 2+浓度（[Ca]i）敏感的机制上，但如果没有钙通过电压依赖性钙通道（VDCC）持续进入细胞，IAS中就没有张力。同样，任何减少VDCC活动的过程（如神经活动）都会减少音调。我们的研究结果在过去的融资期间导致的假设，慢波（SW）在维持国际会计准则的基调发挥了根本性的作用。在下一个资助期，我们研究了ICC和第二种间质细胞类型（称为“PDGFRa+细胞”）在产生SW和IAS中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，其中特定类别的细胞表达各种荧光标记或Ca2+指示剂或关键基因失活。Ca2+成像研究将确定SW起源的位点，并发现哪些细胞对抑制性运动神经支配作出反应。还将收集特定细胞群用于分子分析和膜片钳研究。在可能的情况下，我们还将这些结果应用于食蟹猴（人类的近亲）IAS的平行研究。IAS的功能失调导致大量的社会孤立，失业和制度化，以及美国医疗保健系统每年花费数十亿美元。尽管如此大的医疗保健负担，IAS是胃肠道研究最少的区域。这一建议将把IAS的研究带入细胞分子探针、转基因技术和机制研究的现代时代。这些信息可能为治疗涉及IAS音调不当的排便障碍提供新的理论基础。

 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.