Cell shrinkage evoked by Ca2+-free solution in rat alveolar type II cells:: Ca2+ regulation of Na+-H+ exchange
Cell shrinkage evoked by Ca2+-free solution in rat alveolar type II cells:: Ca2+ regulation of Na+-H+ exchange
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DOI：
10.1113/expphysiol.2004.028837
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发表时间：
2005-03-01
影响因子：
2.7
通讯作者：
Nakahari, T
中科院分区：
文献类型：
--
作者：
Murao, H;Shimizu, A;Nakahari, T
研究了细胞内Ca2+浓度[Ca2+](i)对大鼠肺泡II型细胞（AT-II细胞）体积的影响。在没有或存在amiloride （1 mum，一种Na+通道抑制剂）的情况下，无Ca2+溶液灌注诱导AT-II细胞体积缩小；然而，在5-（n -甲基- n -异丁基）-酰胺（MIA，一种Na+- h +交换抑制剂）存在时，它不存在。MIA使AT-II细胞体积减小。Cl- HCO3-交换抑制剂、4,4'-异硫氰酸二苯乙烯-2,2'-二磺酸（DIDS）和4-乙酰氨基-4'-异硫氰酸二苯乙烯-2,2'-二磺酸（SITS）也能降低AT-II细胞的体积。这表明，无Ca2+溶液引起的细胞收缩是由Na+- h +交换和Cl- HCO3-交换引起的NaCl流入减少引起的。相比之下，加入离子霉素（1mum）后，当用奎宁和阿米洛利预处理AT-II细胞时，细胞肿胀。这种AT-II细胞的肿胀在MIA存在时未被检测到。细胞内pH值（pH(i)）测量表明，无Ca2+溶液或MIA降低了pH(i)，而离子霉素增加了它。离子霉素刺激酸负荷（NH4+脉冲法）后的pH(i)恢复，这在mia处理的AT-II细胞中没有注意到。离子霉素增加fura-2负载AT-II细胞的[Ca2+](i)。综上所述，AT-II细胞的Na+-H+交换活性受[Ca2+](i)调控，维持细胞体积和pH值(i)。
The effects of intracellular Ca2+ concentration, [Ca2+](i), on the volume of rat alveolar type II cells (AT-II cells) were examined. Perfusion with a Ca2+-free solution induced shrinkage of the AT-II cell volume in the absence or presence of amiloride (1 mum, an inhibitor of Na+ channels); however, it did not in the presence of 5-(N-methyl-N-isobutyl)-amiloride (MIA, an inhibitor of Na+-H+ exchange). MIA decreased the volume of AT-II cells. Inhibitors of Cl--HCO3- exchange, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS) also decreased the volume of AT-II cells. This indicates that the cell shrinkage induced by a Ca2+-free solution is caused by a decrease in NaCl influx via Na+-H+ exchange and Cl--HCO3- exchange. Addition of ionomycin (1 mum), in contrast, induced cell swelling when AT-II cells were pretreated with quinine and amiloride. This swelling of the AT-II cells is not detected in the presence of MIA. Intracellular pH (pH(i)) measurements demonstrated that the Ca2+-free solution or MIA decreases pH(i), and that ionomycin increases it. Ionomycin stimulated the pH(i) recovery after an acid loading (NH4+ pulse method), which was not noted in MIA-treated AT-II cells. Ionomycin increased [Ca2+](i) in fura-2-loaded AT-II cells. In conclusion, the Na+-H+ exchange activities of AT-II cells, which maintain the volume and pH(i), are regulated by [Ca2+](i).