Davis C W, Finn A L
Am J Physiol. 1985 Sep;249(3 Pt 1):C304-12. doi: 10.1152/ajpcell.1985.249.3.C304.
Necturus gallbladder epithelium transports sodium and chloride by a process that first involves the cellular entry of each ion across the apical membrane in an electrically silent process. In this paper we present results from cell volume and fluid flux measurements in the presence of different inhibitors and at normal and reduced sodium concentrations, which bear on the process by which ionic entry is effected. We find that reduction of mucosal sodium to a concentration of 10 mM has no effect on either cell volume or on the rate of transepithelial fluid transport, whereas the complete removal of sodium causes a significant decrease in cell volume in addition to its known inhibitory effect on fluid transport. Amiloride had no effect on cell volume at normal sodium concentrations but markedly reduced it when the sodium concentration was reduced to 10 mM. Amiloride, bumetanide, and dipyridamole markedly and reversibly inhibited fluid transport. Finally, the addition of ouabain to the serosal medium induced cell swelling, which was prevented by the removal of potassium from the mucosal medium. These results indicate that the process of sodium entry at the apical membrane is complicated and likely includes both cotransport (NaCl or Na-K-2Cl) and parallel exchange (Na-H and Cl-HCO3) transport mechanisms, and that the proportion of NaCl transported by the different mechanisms varies with the conditions.
美西螈胆囊上皮通过一个过程来转运钠和氯，该过程首先涉及每个离子以电沉默方式穿过顶膜进入细胞。在本文中，我们展示了在存在不同抑制剂以及正常和降低的钠浓度情况下，细胞体积和液体通量测量的结果，这些结果与离子进入所涉及的过程相关。我们发现，将黏膜钠浓度降低到10 mM对细胞体积或跨上皮液体转运速率均无影响，而完全去除钠除了对液体转运有已知的抑制作用外，还会导致细胞体积显著减小。在正常钠浓度下，氨氯地平对细胞体积无影响，但当钠浓度降低到10 mM时，它会显著降低细胞体积。氨氯地平、布美他尼和双嘧达莫显著且可逆地抑制液体转运。最后，向浆膜介质中添加哇巴因会诱导细胞肿胀，而通过从黏膜介质中去除钾可防止这种肿胀。这些结果表明，钠在顶膜进入的过程很复杂，可能包括共转运（NaCl或Na-K-2Cl）和平行交换（Na-H和Cl-HCO3）转运机制，并且不同机制转运的NaCl比例会随条件而变化。
