title: Ion levels in the gastrointestinal tract content of freshwater and marine-estuarine teleosts.
abstract: This study investigated the relationship between ion levels (Na⁺, Cl⁻, K⁺, Ca²⁺, and Mg²⁺) in the fluid phase and total chyme of the contents of the gastrointestinal tract segments of freshwater and marine-estuarine teleosts collected in different salinities (0-34 ppt) in estuarine and freshwater portions of the São Gonçalo channel, southern Brazil. In addition, the relative contribution of feeding and osmoregulation to the ionic content of each portion of the gastrointestinal tract of fishes collected in different ambient salinities was analyzed. There was no relationship between salinity and ion levels in the fluid phase and total chyme of the segments of the gastrointestinal tract when considering all species together. However, there was a significant positive relationship between salinity and ion levels in the fluid phase and total chyme of two fish species (Micropogonias furnieri and Genidens barbus) collected in three or more different salinities. In most species, ion levels in the fluid phase and total chyme changed throughout the gastrointestinal tract, suggesting absorption, but the ionoregulatory mechanisms of the gastrointestinal tract seem to vary according to species.
authors.affiliation: Departamento de Fisiologia e Farmacologia, Universidade Federal de Santa Maria, Santa Maria, RS, 97105-900, Brazil.|Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Alexssandro G
authors.initials: AG
authors.lastname: Becker
authors.affiliation: Departamento de Fisiologia e Farmacologia, Universidade Federal de Santa Maria, Santa Maria, RS, 97105-900, Brazil.
authors.forename: Jamile F
authors.initials: JF
authors.lastname: Gonçalves
authors.affiliation: Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, RS, 96201-900, Brazil.
authors.forename: Marcelo D M
authors.initials: MDM
authors.lastname: Burns
authors.affiliation: Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, RS, 96201-900, Brazil.
authors.forename: João Paes
authors.initials: JP
authors.lastname: Vieira
authors.affiliation: Departamento de Zootecnia, Universidade Federal de Santa Maria, Santa Maria, RS, 97105-900, Brazil.|Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
authors.forename: João
authors.initials: J
authors.lastname: Radünz Neto
authors.affiliation: Departamento de Fisiologia e Farmacologia, Universidade Federal de Santa Maria, Santa Maria, RS, 97105-900, Brazil. bbaldisserotto@hotmail.com.|Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil. bbaldisserotto@hotmail.com.
authors.forename: Bernardo
authors.initials: B
authors.lastname: Baldisserotto
mesh_terms: D000818:Animals; D002397:Catfishes / Q000378:metabolism*; D004435:Eating; D005247:Feeding Behavior; D041981:Gastrointestinal Tract / Q000378:metabolism*; D007477:Ions / Q000378:metabolism*; D010473:Perciformes / Q000378:metabolism*; D054712:Salinity; D014882:Water-Electrolyte Balance
chemical_list: D007477:Ions