Nitric oxide Production and regulation in airway epithelium measured by microsensor

一氧化氮(NO)是由包括呼吸道上皮细胞在内的多种细胞产生的，在呼吸道的生理和炎症过程中发挥着重要作用。在这项研究中，用非选择性微传感器极谱实时测量了培养的上皮细胞产生的NO。本研究旨在探讨NO在呼吸道上皮细胞中的作用。1.呼吸道上皮细胞产生NO牛气管上皮细胞自发产生NO。异丙肾上腺素(ISO)和二丁基环AMP可刺激NO的产生。这种反应可被L-NG-硝基精氨酸甲酯(L-NAME)所抑制。相反，三磷酸腺苷和缓激肽(BK)对NO的产生影响不大。NO对细胞内钙动态的影响L-NAME不改变细胞内钙([Ca^&lt；2+&gt；]i)。然而，用L-NAME而不用D-NAME可抑制ATP和BK诱导的[Ca^&lt；2+&gt；]i的升高，这种抑制作用可被L-精氨酸逆转。此外，硝普钠和二丁基环GMP可增强ATP和BK诱导的[Ca^&lt；2+&gt；]i的升高。这些结果提示，内源性和外源性NO影响呼吸道上皮细胞[Ca^&lt；2+&gt；]i的动力学。3.NO对氯分泌的影响连续监测短路电流(ISC)。L单独给药后ISC下降不明显。用L-NAME(而不是D-NAME)处理细胞，可强烈抑制三磷酸腺苷、BK-和ISO诱导的细胞内皮细胞增殖。这种L诱导的抑制呈剂量依赖性，并被同时加入L-精氨酸所逆转。这些数据表明，内源性NO是激动剂诱导的氯离子分泌的关键分子。

Nitric oxide (NO) is produced from various types of cells including airway epithelial cells and plays an important role in physiologic and inflammatory processes in the airway. In this study, NO production from cultured epithelial cells was measured at real time by NO selective microsensor, polarographically. This study was aimed to determine the role of NO in the airway epithelium.1.NO production from airway epitheliumAirway epithelial cells from cow trachea produced NO spontaneously. Isoproterenol (ISO) and dibutylyl cyclic AMP stimulated NO production. This response was inhibitted by L-NG-nitroarginine methylester (L-NAME). In contrast, ATP and bradykinin (BK) had little effect on NO production. These data suggest that NO production from airway epithelium is mediated via cyclic AMP.2.The effect of NO on Ca^<2+> dynamicsL-NAME did not change baseline level of intracellular calcium ([Ca^<2+>]i). However, pretreatment of the cells with L-NAME,but not D-NAME,inhibited ATP-and BK-induced increase in [Ca^<2+>]i. This inhibitory effect was reversed by L-arginine.Furthermore, pretreatment of the cells with nitroprusside and dibutyryl cyclic GMP potentiated ATP-and BK-induced increase in [Ca^<2+>]i. These results suggest that endogenous and exogenous NO affect Ca^<2+> dynamics in the airway epithelium.3.The effect of NO on Cl secretionThe cell sheets ware mounted in Ussing chamber in the presence of amiloride to assess active Cl secretion. Short circuit current (Isc) was continuously monitored. L-NAME alone induced little decrease in Isc. Pretreatment of the cells with L-NAME,but not D-NAME,strongly inhibited ATP-, BK-and ISO-induced increases in Isc. This L-NAME-induced suppression was dose-dependent and reversed by the simultaneous addition of L-arginine. These data suggest that endogenous NO is a key molecule for agonist-induced Cl secretion.