中文摘要：

本文应用短路电流技术检测了cAMP激动剂forskolin／IBMX和中成药藿香正气水（Huoxiang-zhengqi liquid，HZL）对猪远端气道完整上皮HCO3^-分泌的作用。新鲜分离的气道上皮组织可测得（94．9±8．2）μA/cm^2的跨上皮基础电流，其中的16．6％和62．7％可分别被amiloride（上皮钠离子通道阻断剂，100μmol／L）和NPPB（囊性纤维化跨膜电导调节体Cl^-通道阻断剂，100μmol／L）所阻断。用葡萄糖酸根替代浴液中的Cl^-，跨上皮基础电流降低为（54．0±6．7）μA／cm^2，当进一步替代掉浴液中HCO3^-时，此电流可被去除，提示在未受刺激条件下存在HCO3^-分泌。forskolin／IBMX可刺激HCO3^-依赖的电流增加（7．3±0．5）μA/cm^2。值得注意的是，HZL也能引起HCO3^-电流增加（7．4±1．9）μA／cm^2，而这种刺激作用不受forskolin／IBMX预处理的影响，提示一种不依赖于cAMP的信号通路。以上结果提示，无论是否受刺激，猪远端气道上皮都分泌HCO3^-。托丑对远端气道上皮HCO3^-分泌的刺激作用，提示其有希望成为一种新的、有治疗意义的远端气道HCO3^-分泌刺激剂。

英文摘要：

The short-circuit current （Isc） technique was used to examine the effects of cAMP-evoking agents, forskolin/IBMX, and a Chinese medicinal formula, Huoxiang-zhengqi liquid （HZL） on HCO; secretion by intact porcine distal airway epithelium. The freshly isolated airway epithelial tissue displayed a transepithelial basal current of （94.9±8.2） μA/cm^2, 16.6% and 62.7% of which was inhibited by amiloride （epithelial Na^＋ channel blocker, 100 μmol/L） and NPPB （cystic fibrosis transmembrane conductance regulator Cl^- channel blocker, 100 μmol/L）. Substitution of Cl^- with impermeable gluconate^- in the K-H bath solution resulted in a basal current of （54.0±6.7）μA/cm^2, which could be abolished by further removal of HCO3^- in the solution, indicating HCO3^- secretion under unstimulated conditions. Application of forskolin/IBMX （10 μmol/L/100 μmol/L） stimulated an increase of （13.8± 1.9） μA/cm^2 in Isc which could be blocked by Cl^- channel inhibitor DPC. With Cl^- and Cl^-/HCO3^- substitution, forskolin/IBMX evoked an increase of （7.3±0.5） μ/cm^2 in HCO3^-dependent, DPC-inhibitable Isc （IHCO3）. Noticeably, basolateral application of HZL （10μL/mL） in normal K-H solution evoked an Isc of （15.9±2.4）μA/cm^2. The EC50 of this Isc was （6.1±1.4） μL/mL. When substituting CI-, HZL stimulated an increase of （7.4±1.9） μA/cm^2 in IHCO3, suggesting HZL-induced HCO3 secretion. After pretreating the epithelial tissues with forskolin/IBMX in Cl^--free K-H solution, HZL induced a further increase of （8.4±0.9） μA/cm^2 in IHCO3, and pretreating tissues with HZL did not significantly affect the subsequent forskolin/IBMX-induced IHCO3 response, indicating that HZL- and forskolin/IBMX-induced IHCO3 responses appeared to be independent and be most likely mediated via different cellular mechanisms. Our results suggest that HCOf can be secreted by porcine distal airway epithelium under unstimulated and stimulated conditions, and the stimulatory effect of HZL on HCO