Characterization of plasma membrane Na+/H+ exchange in eel (Anguilla anguilla) intestinal epithelial cells

✍ Scribed by Vilella, S. ;Zonno, V. ;Lapadula, M. ;Verri, T. ;Storelli, C.

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 868 KB
• Volume: 271
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402710103

✦ Synopsis

Abstract

The ability of eel intestinal epithelial cells to recover from an acute acid load was analysed using the fluorescent dye 2′, 7′‐bis‐carboxy‐ethyl‐5, 6‐carboxyfluorescein (BCECF) and cell suspensions. Under these experimental conditions (bicarbonate‐free solutions) the resting pH~i~ in cells prepared from sea‐water (7.52 ± 0.031) and fresh‐water (7.50 ± 0.094) adapted animals proved to be similar. The recovery rate (following an acid load) increases by increasing the Na ion concentration in the extracellular medium. This pH~i~ recovery is competitively inhibited by the specific inhibitor dimethylamiloride (DMA) with a low K~i~ in sea‐ (1.2 μM) as well as in fresh‐water (1.3 μM) adapted animals, indicating the presence of a specific Na/H exchange activity in these cells. Using basolateral membrane vesicles it could be demonstrated that this activity is located on the basolateral side of the enterocyte membrane. The kinetic parameters (K~app~ and J~max~) of this exchanger are similar in fresh‐water and sea‐water adapted animals suggesting that no salinity adaptation occurs, thus excluding the involvement of the antiporter in the osmoregulatory processes. These results are in agreement with the presence in the plasma membrane of the eel enterocytes of a Na/H‐l (housekeeper) form of the antiporter. © 1995 Wiley‐Liss, Inc.