Meeting Abstract

74.6  Friday, Jan. 6  Localization and expression of Na⁺/K⁺-ATPase, Na⁺/K⁺/2Cl^– cotransporter, and CFTR during osmotic challenges to Fundulus grandis. BODINIER, Charlotte*; MENG, Yanling; GALVEZ, Fernando; Louisiana State University, Baton Rouge; Louisiana State University, Baton Rouge; Louisiana State University, Baton Rouge cbodinier@lsu.edu

We investigated the role of Na⁺/K⁺-ATPase (NKA), Na⁺/K⁺/2Cl^– cotransporter (NKCC), and cystic fibrosis transmembrane conductance regulator (CFTR) in transporting epithelia of the gulf killifish, Fundulus grandis, during osmotic challenges. Although NKA was always expressed on the basolateral membrane of epithelia regardless of salinity, the cellular distributions of NKCC and CFTR were salinity-dependent. During seawater acclimation, NKCC and CFTR were mainly co-localized to the apical membrane of the intestine, but were distributed to the basolateral and apical membranes of gills, respectively. Freshwater transfer resulted predominantly in apical NKCC and basolateral CFTR cellular distributions in the intestines and gills. Exposure of fish to intermediate salinities (1 or 5.0 ppt) resulted in mixed cellular distributions of NKCC and CFTR in the gills and intestines, suggesting the presence of mixed cell types in these tissues. We also found that the expression of transport proteins in the kidney varied extensively with salinity, but that these protein-distribution patterns depended on the localization along the kidney tubule. This presentation will describe the potential roles of these proteins in osmoregulation and acid-base regulation during osmotic challenges.