Electroneutral cation-Cl- cotransporters NKCC2β and NCCβ expressed in the intestinal tract of Japanese eel Anguilla japonica.

In the present study, we aimed to elucidate the mechanisms of intestinal Na(+) and Cl(-) absorption in Japanese eel, focusing on electroneutral cation-Cl(-) cotransporters, NKCC2β and NCCβ, expressed in the intestinal tract. First, we cloned cDNAs encoding NKCC2β and NCCβ from the intestinal tract of Japanese eel. In both freshwater- and seawater-acclimated eels, quantitative PCR analysis showed that NKCC2β was predominantly expressed in the anterior and posterior intestines, and that NCCβ expression was specifically high in the rectum.

Rectal water absorption in seawater-adapted Japanese eel Anguilla japonica.

Marine teleosts drink large amounts of seawater to compensate for continuous osmotic water loss. We investigated a possible significant role of the rectum in water absorption in seawater-adapted eel. In rectal sacs filled with balanced salt solution (BSS) and incubated in isotonic BSS, water absorption was greater in seawater-adapted eel than in freshwater eel.