藿香正气水对猪远端气道完整上皮HCO3-分泌的作用

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)μtA/cm2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,100 Ixmol/L)和NPPB(囊性纤维化跨膜电导调节体CI-通道阻断剂,100μmol/L)所阻断.用葡萄糖酸根替代浴液中的CI-,跨上皮基础电流降低为(54.0±6.7)laA/cm2,当进一步替代掉浴液中HCO3-时,此电流可被去除,提示在末受刺激条件下存存HCO3-分泌.forskolin/IBMX可刺激HCO3-依赖的电流增加(7.3±0.5)μA/cm2.值得注意的是,HZL也能引起HCO3-电流增加(7.4±1.9)μA/cm2,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HC03.HZL对远端气道上皮HC03-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.

Effect of Huoxiang-zhengqi liquid on HCO(3)(-) secretion by intact porcine distal airway epithelium

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 HCO3- secretion by intact porcine distal airway epithelium.The freshly isolated airway epithelial tissue displayed a transepithelial basal current of(94.9±8.2)μA/cm2,16.6%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/cm2,which could be abolished by further removal of HCO3- in the solution,indicating HCO3- secretion under unstimulated conditions.Application of forskolin/IBMX(10μmol/L/10μmol/L)stimulated an increase of(13.8±1.9)μA/cm2 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)μA/cm2 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/cm2.The EC50 of this,ISC was(6.1±1.4)μL/mL.When substituting Cl-,HZL stimulated an increase of(7.4±1.9) μA/cm2 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/cm2 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 medihted via different cellular mechanisms.Our results suggest that HCO3- can be secreted by porcine distal airway epithelium under unstimulated and stimulated conditions,and the stimulatory effect of HZL on HCO3- secretion in the distal airway epithelium shows HZL to be a hopeful new agonist for distal airway HCO3- secretion that could be of therapeutic significance.