Collett A, Ramminger S J, Olver R E, Wilson S M
Lung Membrane Transport Group, Tayside Institute of Child Health, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK.
Am J Physiol Lung Cell Mol Physiol. 2002 Apr;282(4):L621-30. doi: 10.1152/ajplung.00142.2001.
Distal lung epithelial cells isolated from fetal rats were cultured (48 h) on permeable supports so that transepithelial ion transport could be quantified electrometrically. Unstimulated cells generated a short-circuit current (I(sc)) that was inhibited (~80%) by apical amiloride. The current is thus due, predominantly, to the absorption of Na(+) from the apical solution. Isoprenaline increased the amiloride-sensitive I(sc) about twofold. Experiments in which apical membrane Na(+) currents were monitored in basolaterally permeabilized cells showed that this was accompanied by a rise in apical Na(+) conductance (G(Na(+))). Isoprenaline also increased apical Cl- conductance (G(Cl-)) by activating an anion channel species sensitive to glibenclamide but unaffected by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). The isoprenaline-evoked changes in G(Na(+)) and G(Cl(minus sign)) could account for the changes in I(sc) observed in intact cells. Glibenclamide had no effect upon the isoprenaline-evoked stimulation of I(sc) or G(Na(+)) demonstrating that the rise in G(Cl-) is not essential to the stimulation of Na(+) transport.
从胎鼠分离的远端肺上皮细胞在可渗透支持物上培养（48小时），以便通过电测定法对跨上皮离子转运进行定量。未受刺激的细胞产生短路电流（I(sc)），该电流被顶端氨氯吡脒抑制（约80%）。因此，该电流主要是由于从顶端溶液中吸收Na(+)所致。异丙肾上腺素使氨氯吡脒敏感的I(sc)增加约两倍。在基底外侧通透的细胞中监测顶端膜Na(+)电流的实验表明，这伴随着顶端Na(+)电导（G(Na(+))）的增加。异丙肾上腺素还通过激活对格列本脲敏感但不受4,4'-二异硫氰酸芪-2,2'-二磺酸（DIDS）影响的阴离子通道种类来增加顶端Cl-电导（G(Cl-)）。异丙肾上腺素引起的G(Na(+))和G(Cl(-))变化可以解释在完整细胞中观察到的I(sc)变化。格列本脲对异丙肾上腺素引起的I(sc)或G(Na(+))刺激没有影响，表明G(Cl-)的增加对Na(+)转运的刺激不是必需的。
