title: Guanylin peptides regulate electrolyte and fluid transport in the Gulf toadfish (Opsanus beta) posterior intestine.
abstract: The physiological effects of guanylin (GN) and uroguanylin (UGN) on fluid and electrolyte transport in the teleost fish intestine have yet to be thoroughly investigated. In the present study, the effects of GN, UGN, and renoguanylin (RGN; a GN and UGN homolog) on short-circuit current (Isc) and the transport of Cl-, Na+, bicarbonate (HCO3-), and fluid in the Gulf toadfish (Opsanus beta) intestine were determined using Ussing chambers, pH-stat titration, and intestinal sac experiments. GN, UGN, and RGN reversed the Isc of the posterior intestine (absorptive-to-secretory), but not of the anterior intestine. RGN decreased baseline HCO3- secretion, but increased Cl- and fluid secretion in the posterior intestine. The secretory response of the posterior intestine coincides with the presence of basolateral NKCC1 and apical cystic fibrosis transmembrane conductance regulator (CFTR), the latter of which is lacking in the anterior intestine and is not permeable to HCO3- in the posterior intestine. However, the response to RGN by the posterior intestine is counterintuitive given the known role of the marine teleost intestine as a salt- and water-absorbing organ. These data demonstrate that marine teleosts possess a tissue-specific secretory response, apparently associated with seawater adaptation, the exact role of which remains to be determined.
authors.affiliation: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and iruhr@rsmas.miami.edu.
authors.forename: Ilan M
authors.initials: IM
authors.lastname: Ruhr
authors.affiliation: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Bodinier
authors.affiliation: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and.
authors.forename: Edward M
authors.initials: EM
authors.lastname: Mager
authors.affiliation: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Esbaugh
authors.affiliation: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and.
authors.forename: Cameron
authors.initials: C
authors.lastname: Williams
authors.affiliation: Ocean Research Institute, University of Tokyo, Tokyo, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takei
authors.affiliation: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and.
authors.forename: Martin
authors.initials: M
authors.lastname: Grosell
mesh_terms: D000818:Animals; D024541:Batrachoidiformes / Q000502:physiology*; D001639:Bicarbonates / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004524:Eels; D005768:Gastrointestinal Hormones / Q000737:chemistry / Q000378:metabolism*; D007422:Intestines / Q000502:physiology*; D008565:Membrane Proteins; D045265:Natriuretic Peptides / Q000737:chemistry / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D012964:Sodium / Q000378:metabolism; D014867:Water / Q000378:metabolism; D014882:Water-Electrolyte Balance / Q000502:physiology*
chemical_list: C438144:ASI1 protein, S cerevisiae; D001639:Bicarbonates; D002712:Chlorides; D018076:DNA, Complementary; D005768:Gastrointestinal Hormones; D008565:Membrane Proteins; D045265:Natriuretic Peptides; D029701:Saccharomyces cerevisiae Proteins; D014867:Water; C072685:guanylin; C084362:uroguanylin; D012964:Sodium
keywords: CFTR; HCO3−; fluid secretion; guanylin; osmoregulation; uroguanylin