Oregon Health & Science Univ., Dept. of Pediatrics, 3181 SW Sam Jackson Park Rd., CDRCP, Portland, OR 97239.
Am J Physiol Lung Cell Mol Physiol. 2014 Feb;306(3):L284-91. doi: 10.1152/ajplung.00163.2013. Epub 2013 Dec 6.
The cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel inhabits the apical membrane of airway epithelia, where its function is essential for mucus hydration, mucociliary clearance, and airway defense. Chronic obstructive pulmonary disease (COPD), most often a consequence of cigarette smoke (CS) exposure, affects 15 million persons in the US. Clinically, COPD is characterized by many of the salient features of cystic fibrosis lung disease, where CFTR is either absent or reduced in function. CS is an acidic aerosol (pH 5.3 to 6.3) reported to contain over 4,000 constituents. Acute CS exposure has been reported to decrease airway transepithelial voltage in vivo and short-circuit current in vitro; however, the mechanistic basis of these effects is uncertain. The goal of the studies described here was to develop a bioassay to characterize the effects of aqueous CS preparations on the channel function of CFTR. We studied aqueous CS extract (CSE) prepared in our laboratory, as well as commercial cigarette smoke condensate (CSC) in Xenopus oocytes expressing human CFTR. Application of CSE at pH 5.3 produced a reversible, voltage-dependent inhibition of CFTR conductance. CSE neutralized to pH 7.3 produced less inhibition of CFTR conductance. Serial dilution of CSE revealed a dose-dependent effect at acidic and neutral pH. In contrast, CSC did not inhibit CFTR conductance in oocytes. We conclude that one or more components of CSE inhibits CFTR in a manner similar to diphenylamine-2-carboxylate, a negatively charged, open-channel blocker.
囊性纤维化跨膜电导调节因子（CFTR）氯离子通道位于气道上皮的顶端膜，其功能对于黏液水合、黏液纤毛清除和气道防御至关重要。慢性阻塞性肺疾病（COPD），最常见的是由于吸烟（CS）暴露的结果，在美国影响了 1500 万人。临床上，COPD 具有许多囊性纤维化肺病的显著特征，CFTR 要么缺失，要么功能降低。CS 是一种酸性气溶胶（pH5.3 至 6.3），据报道含有超过 4000 种成分。据报道，急性 CS 暴露会降低体内气道跨上皮电压和体外短路电流；然而，这些影响的机制基础尚不确定。这里描述的研究旨在开发一种生物测定法来描述水性 CS 制剂对 CFTR 通道功能的影响。我们研究了我们实验室制备的水性 CS 提取物（CSE），以及在表达人 CFTR 的非洲爪蟾卵母细胞中商业香烟烟雾冷凝物（CSC）。在 pH5.3 时应用 CSE 产生 CFTR 电导的可逆、电压依赖性抑制。中性化至 pH7.3 的 CSE 产生的 CFTR 电导抑制作用较小。CSE 的连续稀释在酸性和中性 pH 下显示出剂量依赖性效应。相比之下，CSC 不会抑制卵母细胞中的 CFTR 电导。我们得出结论，CSE 的一个或多个成分以类似于二苯胺-2-羧酸的方式抑制 CFTR，二苯胺-2-羧酸是一种带负电荷的开放通道阻滞剂。
