Lee M C, Penland C M, Widdicombe J H, Wine J J
Cystic Fibrosis Research Laboratory, Stanford University, California 94305-2130, USA.
Am J Physiol. 1998 Mar;274(3):L450-3. doi: 10.1152/ajplung.1998.274.3.L450.
The Calu-3 cell line is being investigated as a model for human submucosal gland serous cells. In a previous investigation of basal short-circuit current (Isc) in Calu-3 cells, high levels of bumetanide-insensitive basal Isc (approximately 60 microA/cm2) were measured in cells grown at an air interface. Basal Isc was reduced only 7% by bumetanide, and the largest component of basal Isc required both Cl- and HCO3- in the bathing solutions. Because Isc could be partially inhibited by basolateral 4,4'-dinitrostilbene-2,2'-disulfonic acid and because the only known apical exit pathway for anions is the cystic fibrosis transmembrane conductance regulator, which has a relatively poor conductance for HCO3-, it was concluded that most basal Isc is HCO3(-)-dependent Cl- secretion [M. Singh, M. Krouse, S. Moon, and J. J. Wine. Am. J. Physiol. 272 (Lung Cell. Mol. Physiol. 16): L690-L698, 1997]. We have now measured isotopic fluxes of 36Cl- and 22Na+ across short-circuited Calu-3 cells and found that virtually none of the basal Isc is Cl- secretion or Na+ absorption. Thus, in contrast to the earlier report, we conclude that the major component of basal Isc is HCO3- secretion. Stimulation recruits primarily Cl- secretion, as previously proposed.
Calu-3细胞系正作为人类黏膜下腺浆液细胞的模型进行研究。在先前对Calu-3细胞基础短路电流（Isc）的研究中，在空气界面培养的细胞中测量到高水平的布美他尼不敏感基础Isc（约60微安/平方厘米）。布美他尼仅使基础Isc降低了7%，基础Isc的最大成分在浴液中需要Cl-和HCO3-。由于Isc可被基底外侧的4,4'-二硝基芪-2,2'-二磺酸部分抑制，且已知阴离子唯一的顶端排出途径是囊性纤维化跨膜传导调节因子，其对HCO3-的传导性相对较差，因此得出结论，大多数基础Isc是HCO3-依赖性Cl-分泌[M. Singh, M. Krouse, S. Moon, and J. J. Wine. Am. J. Physiol. 272 (Lung Cell. Mol. Physiol. 16): L690-L698, 1997]。我们现在测量了36Cl-和22Na+跨短路Calu-3细胞的同位素通量，发现几乎没有基础Isc是Cl-分泌或Na+吸收。因此，与早期报告相反，我们得出结论，基础Isc的主要成分是HCO3-分泌。如先前提出的那样，刺激主要募集Cl-分泌。
