title: AVT and IT regulate ion transport across the opercular epithelium of killifish (Fundulus heteroclitus) and gilthead sea bream (Sparus aurata).
abstract: The regulatory role of arginine vasotocin (AVT) and isotocin (IT) in Cl(-) secretion was investigated with the short circuit current (Isc) technique in opercular epithelia of killifish (Fundulus heteroclitus) and gilthead sea bream (Sparus aurata). Sea bream operculum showed ~4-fold lower number of Na/K-ATPase immunoreactive cells and ~12-fold lower secretory current than the killifish. In sea bream opercular membranes, the basolateral addition of AVT (10(-6) M) significantly stimulated Cl(-) secretion, while IT (10(-6) M) was without effect. In killifish, IT produced an immediate dose-dependent stimulation of Cl(-) secretion with significant effect at doses ≥10(-7) M and stimulation maxima (∆Isc ~25 μA⋅cm(-2)) at 10(-6) M. The basolateral addition of bumetanide (200 μM) abolished >75% of the effect of IT on Cl(-) secretion. In turn, AVT had a dual effect on killifish opercular Isc: an immediate response (~3min) with Isc reduction in an inverted bell-shaped dose-response manner with higher current decrease (-22 μA⋅cm(-2)) at 10(-8) M AVT, and a sustained dose-dependent stimulation of Cl(-) secretion (stable up to 1h), with a threshold significant effect at 10(-8) M and maximal stimulation (~20 μA⋅cm(-2)) at 10(-6)M. Both effects of AVT appear receptor type specific. The V1-receptor antagonist SR 49059 abolished Isc reduction in response to AVT, while the specific V2-receptor antagonist (Tolvaptan, 1 μM) abolished the stimulatory action of AVT on Cl(-) secretion. According to these results, we propose a modulatory role for AVT and IT in Cl(-) (NaCl) secretion across the opercular epithelium of marine teleost.
authors.affiliation: Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro 8005-139, Portugal; Campus de Excelencia Internacional del Mar (CEI-MAR), Instituto de Ciencias Marinas de Andalucía, Consejo Superior Investigaciones Científicas (ICMAN-CSIC), Puerto Real, Cádiz E-11510, Spain; Campus de Excelencia Internacional del Mar (CEI-MAR), Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Puerto Real, Cádiz E-11510, Spain.
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Martos-Sitcha
authors.affiliation: Campus de Excelencia Internacional del Mar (CEI-MAR), Instituto de Ciencias Marinas de Andalucía, Consejo Superior Investigaciones Científicas (ICMAN-CSIC), Puerto Real, Cádiz E-11510, Spain.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: MartínezRodríguez
authors.affiliation: Campus de Excelencia Internacional del Mar (CEI-MAR), Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Puerto Real, Cádiz E-11510, Spain.
authors.forename: Juan Miguel
authors.initials: JM
authors.lastname: Mancera
authors.affiliation: Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro 8005-139, Portugal. Electronic address: jfuentes@ualg.pt.
authors.forename: Juan
authors.initials: J
authors.lastname: Fuentes
mesh_terms: D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D002034:Bumetanide / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004848:Epithelium / Q000378:metabolism; D029941:Fish Proteins / Q000378:metabolism; D023781:Fundulidae / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D017136:Ion Transport / Q000187:drug effects; D010121:Oxytocin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D017483:Receptors, Vasopressin; D021541:Sea Bream / Q000378:metabolism*; D000077602:Tolvaptan; D014668:Vasotocin / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D001552:Benzazepines; D002712:Chlorides; D029941:Fish Proteins; D007211:Indoles; D011759:Pyrrolidines; D017483:Receptors, Vasopressin; C034862:vasotocin receptor; D002034:Bumetanide; D000077602:Tolvaptan; D010121:Oxytocin; C008215:isotocin; C082134:relcovaptan; D014668:Vasotocin
keywords: Fundulus heteroclitus; Ion transport; Isotocin; Operculum; Sparus aurata; Vasotocin