SODIUM AND CATION CHANNELS IN CYSTIC FIBROSIS

虽然我们知道整流氯离子通道是有缺陷的， 突变型CFTR表达与囊性纤维化的关系 跨膜传导调节因子（CFTR）和其他离子通道， 囊性纤维化（CF）组织是未知的。 囊性纤维化（CF）也是 其特征在于增加的钠吸收。 这增加了钠 吸收增加了减少的氯化物分泌， 体液平衡正常 如果钠吸收过度或正常钠 吸收可以被抑制，它可以减轻受损的液体平衡。 CF中钠缺乏的细胞基础尚不清楚。 一 可能是通过阿米洛利敏感的钠增加吸收 渠道 由于核苷酸门控阳离子通道是丰富的 表达于肺（支气管和细支气管）和肠（绒毛细胞），两个 参与囊性纤维化的器官，该通道也可能有助于 钠的过度吸收 如果核苷酸门控阳离子通道 参与正常钠吸收或过量钠吸收 在CF中，该通道上的二氯苯脒抑制位点可能是 治疗干预的潜在部位。 具体目标是：1） 评估核苷酸门控阳离子通道是否有助于钠离子通道 通过测定a）分布， 核苷酸门控通道的原位杂交 腺体、胰腺细胞和鼻上皮B）免疫细胞化学 肺、肠、胰腺和汗腺中通道的定位 以及c）核苷酸门控通道对短路的贡献 大鼠气管细胞电流。 2)为了评估 阿米洛利敏感钠通道和核苷酸门控阳离子通道 和CFTR通过共转染核苷酸门控通道与突变或 正常CFTR用于研究通道的特性， 导致钠的过度吸收 将进行比较 使用全细胞和单通道记录。 3)克隆，然后 表征的药理学和电生理学特性 通过表达新的肠核苷酸门控阳离子通道 卵母细胞中的cDNA克隆。 为了确定二氯苯扎明是否阻断了 调节核苷酸门控通道的孔。

Although we know that the rectifying chloride channel is defective when mutant CFTR is expressed, the relationship between the cystic fibrosis transmembrane conductance regulator (CFTR) and other ion channels in cystic fibrosis (CF) tissues is not known. Cystic fibrosis (CF) is also characterized by increased sodium absorption. This increased sodium absorption adds to the reduced chloride secretion to further diminish normal fluid balance. If sodium hyperabsorption or normal sodium absorption can be inhibited, it may mitigate compromised fluid balance. The cellular basis of the sodium defect in CF is unknown. One possibility is increased absorption through amiloride-sensitive sodium channels. Since nucleotide-gated cation channels are abundantly expressed in lung (bronchi and bronchioles) and gut, (villus cells), two organs involved in cystic fibrosis, this channel may also contribute to hyperabsorption of sodium. If nucleotide-gated cation channels participate in normal sodium absorption or excessive sodium absorption in CF, the dichlorobenzamil inhibitory site on this channel may be a potential site for therapeutic intervention. The Specific Aims are: 1) To evaluate whether nucleotide-gated cation channels contribute to sodium absorption in tissues involved in CF by determining a) the distribution of nucleotide-gated channels by in situ hybridization in normal seat glands, pancreatic cells and the nasal epithelium b) immunocytochemical localization of the channel in lung, intestine, pancreas and sweat glands and c) the contribution of nucleotide-gated channels to short circuit current of rat tracheal cells. 2) To evaluate the interaction between amiloride-sensitive sodium channels and nucleotide-gated cation channels and CFTR by cotransfection of nucleotide-gated channels with mutated or normal CFTR for study of the properties of channels which may be responsible for hyperabsorption of sodium. Comparisons will be made using whole-cell and single channel recordings. 3) To clone, then characterize the pharmacological and electrophysiological properties of the novel intestinal nucleotide-gated cation channel by expression of cDNA clone(s) in oocytes. To determine if dichlorobenzamil blocks the condition pore of the nucleotide-gated channel.