[Ca2+]i and Secretory Dynamics in Parotid Acinar Cells

唾液对口腔健康至关重要。它对口腔粘膜的水合作用至关重要;它提供润滑，开始 营养消化和赋予抗菌和机械保护的嘴和鞋面 胃肠道唾液流量减少（口干症）极大地影响了患者的生活质量。一个关键 唾液的液体和蛋白质组分两者的促分泌素刺激中的事件是唾液中的促分泌素的增加。 胞质游离钙浓度[Ca 2 +]i. [Ca 2 +]i的这种增加具有特定的时间和空间 这些特征被认为对于适当地激活效应器是重要的， 唾液的分泌乙酰胆碱和大多数其他促分泌素以促代谢方式起作用 刺激1，4，5-三磷酸肌醇（InsPS）的产生和细胞内Ca 2+的释放。在 在唾液腺泡细胞中，Ca 2+信号也可以通过替代的，很大程度上独立的离子型 三磷酸腺苷（ATP）激活P2 X类Ca 2+可渗透离子后的过程 渠道后一种机制将被预测为导致Ca 2+信号和效应物激活， 具有鲜明的时空特征。利用现代光学技术，如数字成像， 全内反射显微镜和共聚焦显微镜结合转基因动物模型， 具体药理学，我们将扩大在孤立的唾液腺腺泡中产生的发现，以确定钙离子 通过代谢型和特别是通过离子型P2 X4嘌呤能刺激的信号传导事件 受体（P2 X4 R）刺激的器官型腮腺切片制备（目的1）。Ca 2+信号作为 P2 X4 R激活的结果在蛋白激酶A（PKA）激活后显著增强。因为流体 当PKA被激活时，分泌也增强，这可能是生理学上相关的情况。在 具体目标2我们建议确定这一事件背后的分子机制。具体目标3a 主要目标是评估是否通过P2 X4受体（P2 X4 R）的离子型嘌呤能信号传导， 单独或在特定的药理学操作之后是流体的有效活化剂， 胞吐分泌机制这些研究旨在促进我们对复杂的理解 一系列调节分子事件，导致液体分泌，并可能最终导致设计 基于利用口腔粘膜中残留的 功能性腺泡组织

Saliva is vital for oral health. It is essential for the hydration of the oral mucosa; it provides lubrication, begins nutrient digestion and imparts antimicrobial and mechanical protection for the mouth and upper gastrointestinal tract. Reduced flow of saliva (xerostomia) greatly impact the quality of life of suffers. A key event in the secretagogue stimulation of both the fluid and protein component of saliva is an increase in the cytosolic free calcium concentration [Ca2+]i. This increase in [Ca2+]i has specific temporal and spatial characteristics which are thought to be important for appropriately activating effectors important for the secretion of saliva. Acetylcholine and the majority of other secretagogues act in a metabotropic manner stimulating the production of inositol 1,4,5-trisphosphate (InsPS) and the release of intracellular Ca2+. In salivary acinar cells, Ca2+ signals can also be generated by an alternative, largely independent ionotropic process following adenosine triphosphate (ATP) activation of the P2X class of Ca2+ permeable ion channels. The latter mechanism would be predicted to result in Ca2+ signals and effector activation with distinct spatial and temporal characteristics. Using contemporary optical techniques such as digital imaging, total internal reflection microscopy and confocal microscopy combined with transgenic animal models and specific pharmacology we will expand on findings generated in isolated salivary gland acini to define Ca2+ signaling events stimulated through both metabotropic and in particular through ionotropic P2X4 purinergic receptor (P2X4R) stimulation in an organotypic parotid gland slice preparation (aim 1). Ca2+ signals as a result of P2X4R activation are profoundly enhanced following protein kinase A (PKA) activation. Since fluid secretion is also enhanced when PKA is activated this may be the physiologically relevant situation. In specific aim 2 we propose to define the molecular mechanism underlying this event. In specific aim 3 a primary goal will be to assess whether ionotropic purinergic signaling through P2X4 receptors (P2X4R), either alone, or following specific pharmacological manipulation is an effective activator of the fluid and exocytotic secretion mechanism. These studies are designed to advance our understanding of the complex series of regulated molecular events which result in fluid secretion and may ultimately lead to the design of therapeutic strategies for the treatment of xerostomia based on exploiting the physiology of remaining functional acinar tissue.