title: AVT is involved in the regulation of ion transport in the intestine of the sea bream (Sparus aurata).
abstract: The intestine of marine fish plays a crucial role in ion homeostasis by selective processing of ingested fluid. Although arginine vasotocin (AVT) is suggested to play a role in ion regulation in fish, its action in the intestine has not been demonstrated. Thus, the present study investigated in vitro the putative role of AVT in intestinal ion transport in the sea bream (Sparus aurata). A cDNA encoding part of an AVT receptor was isolated and phylogenetic analysis revealed it clustered with the V1a2-type receptor clade. V1a2 transcripts were expressed throughout the gastrointestinal tract, from esophagus to rectum, and were most abundant in the rectum regardless of long-term exposure to external salinities of 12, 35 or 55p.p.t. Basolateral addition of AVT (10(-6)M) to the anterior intestine and rectum of sea bream adapted to 12, 35 or 55p.p.t. mounted in Ussing chambers produced rapid salinity and region dependent responses in short circuit current (Isc), always in the absorptive direction. In addition, AVT stimulation of absorptive Isc conformed to a dose-response curve, with significant effects achieved at 10(-8)M, which corresponds to physiological values of plasma AVT for this species. The effect of AVT on intestinal Isc was insensitive to the CFTR selective inhibitor NPPB (200μM) applied apically, but was completely abolished in the presence of apical bumetanide (200μM). We propose a role for AVT in the regulation of ion absorption in the intestine of the sea bream mediated by an absorptive bumetanide-sensitive mechanism, likely NKCC2.
authors: Centre of Marine Sciences (CCMar), CIMAR - Laboratório Associado, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, E-11510 Puerto Real (Cádiz), Spain; Instituto de Ciencias Marinas de Andalucía, Consejo Superior Investigaciones Científicas (ICMAN-CSIC), E-11510 Puerto Real (Cádiz), Spain.
authors: Juan Antonio
authors: JA
authors: Martos-Sitcha
authors: Silvia Filipa
authors: SF
authors: Gregório
authors: Edison Samir M
authors: ES
authors: Carvalho
authors: Adelino Vicente M
authors: AV
authors: Canario
authors: Deborah Mary
authors: DM
authors: Power
authors: Juan Miguel
authors: JM
authors: Mancera
authors: Gonzalo
authors: G
authors: Martínez-Rodríguez
authors: Juan
authors: J
authors: Fuentes
mesh_terms: D000818:Animals; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000378:metabolism; D064587:Osmoregulation / Q000235:genetics / Q000502:physiology; D021541:Sea Bream / Q000378:metabolism*; D014668:Vasotocin / Q000235:genetics / Q000378:metabolism*; D014867:Water / Q000378:metabolism
chemical_list: D029941:Fish Proteins; D014867:Water; D014668:Vasotocin
keywords: Arginine vasotocin; Osmoregulation; Salinity; Sea bream; Water absorption