Gerard C, Gabrion J, Verrier B, Reggio H, Mauchamp J
Eur J Cell Biol. 1985 Jul;38(1):134-41.
The Na+/K+-ATPase was localized using purified specific antibodies, on the basolateral membranes of rat thyroid epithelial cells and of cultured porcine thyroid cells, by immunofluorescence and immunoelectron microscopy. No staining was observed on the apical membranes. When cultured cells formed monolayers, with their apical pole in contact with the culture medium, 22Na+ uptake was inhibited by amiloride. Inhibition was dependent upon extracellular Na+ concentration, half maximal inhibition was obtained with 0.7 microM amiloride in the presence of 5 mM Na+. Ouabain was ineffective on Na+ uptake into intact monolayers. A brief treatment of the monolayers with ethyleneglycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) opened the tight junctions and allowed the access of ouabain to the basal pole of the cells. In this condition ouabain increased Na+ uptake. When cells were reorganized into follicle-like structures, with their basal pole in contact with the culture medium, Na+ uptake was not modified by amiloride but was increased by ouabain. We conclude that in thyroid cells, the Na+/K+-ATPase is present on the basolateral domain of the plasma membrane whereas an amiloride sensitive sodium uptake occurs at the apical surface.
利用纯化的特异性抗体，通过免疫荧光和免疫电子显微镜技术，将钠钾ATP酶定位在大鼠甲状腺上皮细胞和培养的猪甲状腺细胞的基底外侧膜上。在顶膜上未观察到染色。当培养细胞形成单层，其顶端极与培养基接触时，阿米洛利可抑制22Na+摄取。抑制作用取决于细胞外钠浓度，在5 mM钠存在下，0.7 microM阿米洛利可获得半数最大抑制。哇巴因对完整单层细胞摄取钠无效。用乙二醇双（β-氨基乙醚）-N，N，N'，N'-四乙酸（EGTA）对单层细胞进行短暂处理可打开紧密连接，使哇巴因能够进入细胞的基底极。在这种情况下，哇巴因可增加钠摄取。当细胞重组为类滤泡结构，其基底极与培养基接触时，阿米洛利不改变钠摄取，但哇巴因可增加钠摄取。我们得出结论，在甲状腺细胞中，钠钾ATP酶存在于质膜的基底外侧结构域，而阿米洛利敏感的钠摄取发生在顶端表面。
