title: Efferent pathways in sodium overload-induced renal vasodilation in rats.
abstract: Hypernatremia stimulates the secretion of oxytocin (OT), but the physiological role of OT remains unclear. The present study sought to determine the involvement of OT and renal nerves in the renal responses to an intravenous infusion of hypertonic saline. Male Wistar rats (280-350 g) were anesthetized with sodium thiopental (40 mg. kg(-1), i.v.). A bladder cannula was implanted for collection of urine. Animals were also instrumented for measurement of mean arterial pressure (MAP) and renal blood flow (RBF). Renal vascular conductance (RVC) was calculated as the ratio of RBF by MAP. In anesthetized rats (n = 6), OT infusion (0.03 µg • kg(-1), i.v.) induced renal vasodilation. Consistent with this result, ex vivo experiments demonstrated that OT caused renal artery relaxation. Blockade of OT receptors (OXTR) reduced these responses to OT, indicating a direct effect of this peptide on OXTR on this artery. Hypertonic saline (3 M NaCl, 1.8 ml • kg(-1) b.wt., i.v.) was infused over 60 s. In sham rats (n = 6), hypertonic saline induced renal vasodilation. The OXTR antagonist (AT; atosiban, 40 µg • kg(-1) • h(-1), i.v.; n = 7) and renal denervation (RX) reduced the renal vasodilation induced by hypernatremia. The combination of atosiban and renal denervation (RX+AT; n = 7) completely abolished the renal vasodilation induced by sodium overload. Intact rats excreted 51% of the injected sodium within 90 min. Natriuresis was slightly blunted by atosiban and renal denervation (42% and 39% of load, respectively), whereas atosiban with renal denervation reduced sodium excretion to 16% of the load. These results suggest that OT and renal nerves are involved in renal vasodilation and natriuresis induced by acute plasma hypernatremia.
authors.affiliation: Center for Neuroscience and Cardiovascular Physiology, Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Nathalia O
authors.initials: NO
authors.lastname: Amaral
authors.affiliation: Center for Neuroscience and Cardiovascular Physiology, Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Thiago S
authors.initials: TS
authors.lastname: de Oliveira
authors.affiliation: Center for Neuroscience and Cardiovascular Physiology, Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Lara M
authors.initials: LM
authors.lastname: Naves
authors.affiliation: Center for Neuroscience and Cardiovascular Physiology, Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Filgueira
authors.affiliation: Faculty of Physical Education, Biological Sciences Institute, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Marcos L
authors.initials: ML
authors.lastname: Ferreira-Neto
authors.affiliation: Department of Physiology, Federal University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Gerard H M
authors.initials: GH
authors.lastname: Schoorlemmer
authors.affiliation: Center for Neuroscience and Cardiovascular Physiology, Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Carlos H
authors.initials: CH
authors.lastname: de Castro
authors.affiliation: Center for Neuroscience and Cardiovascular Physiology, Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: André H
authors.initials: AH
authors.lastname: Freiria-Oliveira
authors.affiliation: Center for Neuroscience and Cardiovascular Physiology, Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Carlos H
authors.initials: CH
authors.lastname: Xavier
authors.affiliation: Center for Neuroscience and Cardiovascular Physiology, Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Diego B
authors.initials: DB
authors.lastname: Colugnati
authors.affiliation: Center for Neuroscience and Cardiovascular Physiology, Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Rosa
authors.affiliation: Center for Neuroscience and Cardiovascular Physiology, Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Graziela T
authors.initials: GT
authors.lastname: Blanch
authors.affiliation: Laboratory of Molecular Biology, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Clayton L
authors.initials: CL
authors.lastname: Borges
authors.affiliation: Laboratory of Molecular Biology, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Célia M A
authors.initials: CM
authors.lastname: Soares
authors.affiliation: Department of Biochemistry and Molecular Biology, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Angela A S
authors.initials: AA
authors.lastname: Reis
authors.affiliation: Department of Physiology, Federal University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Sergio L
authors.initials: SL
authors.lastname: Cravo
authors.affiliation: Center for Neuroscience and Cardiovascular Physiology, Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Gustavo R
authors.initials: GR
authors.lastname: Pedrino
mesh_terms: D000818:Animals; D004525:Efferent Pathways; D006339:Heart Rate; D006955:Hypernatremia / Q000503:physiopathology*; D008297:Male; D010120:Oxytocics / Q000494:pharmacology; D010121:Oxytocin / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D018045:Receptors, Oxytocin / Q000235:genetics / Q000378:metabolism; D012077:Renal Artery / Q000187:drug effects / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D010120:Oxytocics; D012333:RNA, Messenger; D018045:Receptors, Oxytocin; D012462:Saline Solution, Hypertonic; D010121:Oxytocin