REGULATION OF INTESTINAL ION CHANNELS

旅行者的腹泻通常是由大肠杆菌引起的，它会释放一种 热稳定毒素(Sta)增加环鸟苷酸(CGMP)。STA生成cGMP 通过激活膜上结合的鸟苷环化酶从GTP中分离出来。这 该提案旨在确定哪些氯离子通道参与 水盐平衡，并研究国家海洋局和国家海洋局 CGMP。跨上皮细胞模型培养的结肠癌细胞株T84 氯化物分泌，表现出静态刺激的短路电流，a 跨上皮运输的量度。StA对氯化物的调节 培养的T84细胞中的通道，将与研究并行探索 在回肠细胞上。 利用T84细胞，第一个目标是研究生物物理 用全细胞膜片法研究STA诱导的氯电流特性 钳夹技术，并确定是否使用切除的补片如果被激活 氯通道受cGMP依赖的蛋白激酶的调节。这个 第二个目标是确定STA激活的相互关系 氯离子电流和由其他氯离子分泌物激活的电流 血管活性肠肽和卡巴胆碱等激动剂。第三个目标 是通过增加我们对回肠氯离子通道的了解 研究它们的性质和控制机制。 全电池电流和单通道波动都将 量过了。全细胞电流模式的优点是个体 可以将信号与其他伴随信号隔离进行测试。 单声道录音确定了所谓的秘密 通道位于根尖膜上。 这项工作的长期目标是隔离参与的通道 在控制肠道中的盐分和液体的运动中 记录他们在健康和腹泻状态下的监管控制。

Traveller's diarrhea is often caused by Escherichia coli which releases a heat-stable toxin (STa) increasing cyclic GMP (cGMP). STa generates cGMP from GTP by activation of a membrane bound guanylate cyclase. This proposal is designed to identify which chloride channels are involved in fluid and salt balance and to investigate their regulation by STa and cGMP. The cultured colonic cell line, T84, a model for transepithelial chloride secretion, exhibits STa-stimulated short circuit current, a measure of transepithelial transport. STa regulation of chloride channels in cultured T84 cells, will be explored in parallel with studies on ileal cells. Using T84 cells, the first aim is to investigate the biophysical properties of STa-induced chloride currents using the whole cell patch clamp technique and to determine using excised patches if STa-activated chloride channels are modulated by cGMP-dependent protein kinase. The second aim is to determine the interrelationship between STa-activated chloride currents and those activated by other chloride secretory agonists like vasoactive intestinal peptide and carbachol. The third aim is to increase our understanding of chloride channels in the ileum by investigating their properties and control mechanisms. Both whole-cell currents and single channel fluctuations will be measured. The whole-cell current mode has the advantage that individual signals can be tested in isolation from other concomitant signals. Single channel recordings determine whether the purported secretory channels are located on the apical membrane. The long term goal of this work is to isolate channels which participate in the control of salt and fluid movements in the intestine and to document their regulatory control in health and in diarrheal states.