Intestinal water absorption through aquaporin 1 expressed in the apical membrane of mucosal epithelial cells in seawater-adapted Japanese eel
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- Mayumi Aoki
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
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- Toyoji Kaneko
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
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- Fumi Katoh
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
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- Sanae Hasegawa
- Ocean Research Institute, University of Tokyo, Nakano, Tokyo 164-8639,Japan
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- Naoaki Tsutsui
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
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- Katsumi Aida
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
抄録
<jats:title>SUMMARY</jats:title><jats:p>To elucidate the mechanisms associated with water absorption in the intestine, we compared drinking and intestinal water absorption in freshwater-and seawater-adapted Japanese eels, and investigated a possible involvement of aquaporin (AQP) in the absorption of water in the intestine. Seawater eels ingested more water than freshwater eels, the drinking rate being 0.02 ml kg-1 h-1 in fresh water and 0.82 ml kg-1h-1 in sea water. In intestinal sacs prepared from freshwater and seawater eels, water absorption increased in time- and hydrostatic pressure-dependent manners. The water absorption rates were greater in seawater sacs than in freshwater sacs, and also greater in the posterior intestine than in the anterior. In view of the enhanced water permeability in the intestine of seawater eel, we cloned two cDNAs encoding AQP from the seawater eel intestine, and identified two eel homologues (S-AQP and L-AQP) of mammalian AQP1. S-AQP and L-AQP possessed the same amino acid sequence, except that one amino acid was lacking in S-AQP and two amino acids were substituted. Eel AQP1 was expressed predominantly in the intestine, and the expression levels were higher in seawater eel than in freshwater eel. Immunocytochemical studies revealed intense AQP1 immunoreaction in the apical surface of columnar epithelial cells in seawater eel, in which the immunoreaction was stronger in the posterior intestine than in the anterior. In contrast, the immunoreaction was faint in the freshwater eel intestine. Preferential localization of AQP1 in the apical membrane of epithelial cells in the posterior intestine of seawater eel indicates that this region of the intestine is responsible for water absorption, and that AQP1 may act as a water entry site in the epithelial cells.</jats:p>
収録刊行物
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- Journal of Experimental Biology
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Journal of Experimental Biology 206 (19), 3495-3505, 2003-10-01
The Company of Biologists
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詳細情報
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- CRID
- 1361981469313427200
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- NII論文ID
- 30002329865
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- ISSN
- 14779145
- 00220949
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