TRANSPORT IN SMALL PANCREATIC DUCTS

外分泌分泌盐、水和消化酶 大多数囊性纤维化患者的胰腺严重受损 (Cf)。这种疾病是由囊性纤维化的突变引起的。 跨膜电导调节蛋白(CFTR)作为一种 CAMP依赖的氯离子通道。最近的免疫定位研究 结果表明，CFTR在卵巢癌组织中的表达水平较高。 排列在小胰管内的上皮细胞。相比之下， CFTR在大胰管中的表达水平较低， 在腺泡细胞中检测不到。导管上皮细胞仅由 占胰腺体积的5%-10%，埋在腺泡内 组织，因此很难进行研究。正因为如此 限制，大多数关于导管细胞转运功能的结论是 基于转运抑制剂对体积和 从体内或体外收集的分泌物的组成 整个胰腺。因此，我们对正常导管细胞的了解 运输功能贫乏，我们对胰腺的认识 CF的病理生理学是有限的。这项提案的总体目标是 是为了对跨上皮细胞有一个定量的了解 小胰管的运输特性，并确定 CFTR在导管碳酸氢钠分泌中的精确作用。 具体地说，我们将使用隔离灌流的小叶内和小叶间。 导管节段测定基础刺激率和分泌素刺激率 液体分泌物，分泌物液体的离子成分，以及 导管上皮的跨上皮电特性。 常规和离子选择性细胞内微电极技术 Win被用来识别运输路径并确定 根尖细胞和基底外侧细胞的电化学驱动力 负责跨上皮运输的膜。最后，程度 导管对其保留了差异化的传输特性 在单层培养中生长的上皮细胞将被测定。这个 从这些研究中获得的信息将被用来关键地 更清楚地评估目前胰腺导管分泌的模型 明确cftr在导管功能中的作用，并为 永生化导管上皮细胞系的评价。

The secretion of salt, water, and digestive enzymes by the exocrine pancreas is severely compromised in most patients with cystic fibrosis (CF). The disease results from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) protein which functions as a cAMP-dependent chloride channel. Recent immunolocalization studies demonstrated that the level of expression of CFTR is high in the epithelial cells that line the small pancreatic ducts. In contrast, the level of expression of CFTR is low in large pancreatic ducts, and is undetectable in acinar cells. The ductal epithelial cells comprise only 5-10% of the volume of the pancreas and are buried within the acinar tissue, and thus poorly accessible for study. Because of these limitations, most conclusions about ductal cell transport function are based upon the effects of transport inhibitors on the volume and composition of secretions collected either in vivo or in vitro from the whole pancreas. Consequently, our knowledge of normal ductal cell transport function is meager, and our understanding of pancreatic pathophysiology in CF is limited. The overall objective of this proposal is to obtain a quantitative understanding of the transepithelial transport properties of small pancreatic ducts, and to determine the precise role of CFTR in ductal sodium bicarbonate secretion. Specifically, we will use isolated perfused intra- and inter-lobular ductal segments to determine the basal and secretin stimulated rates of fluid secretion, the ionic composition of the secreted fluid, and the transepithelial electrical properties of the ductal epithelium. Conventional and ion-selective intracellular microelectrode techniques win be used to identify transport pathways and to determine electrochemical driving forces at the apical and basolateral cell membranes responsible for transepithelial transport. Finally, the extent to which differentiated transport properties are retained by ductal epithelial cells grown in monolayer culture will be determined. The information obtained from these studies will be used to critically evaluate current models of pancreatic ductal secretion, more clearly define the role of CFTR in ductal function, and to provide a basis for evaluation of immortalized ductal epithelial cell lines.