title: Renal actions of atrial natriuretic peptide in spontaneously hypertensive rats: the role of nitric oxide as a key mediator.
abstract: Atrial natriuretic peptide (ANP) is an important regulator of blood pressure (BP). One of the mechanisms whereby ANP impacts BP is by stimulation of nitric oxide (NO) production in different tissues involved in BP control. We hypothesized that ANP-stimulated NO is impaired in the kidneys of spontaneously hypertensive rats (SHR) and this contributes to the development and/or maintenance of high levels of BP. We investigated the effects of ANP on the NO system in SHR, studying the changes in renal nitric oxide synthase (NOS) activity and expression in response to peptide infusion, the signaling pathways implicated in the signaling cascade that activates NOS, and identifying the natriuretic peptide receptors (NPR), guanylyl cyclase receptors (NPR-A and NPR-B) and/or NPR-C, and NOS isoforms involved. In vivo, SHR and Wistar-Kyoto rats (WKY) were infused with saline (0.05 ml/min) or ANP (0.2 μg·kg(-1)·min(-1)). NOS activity and endothelial (eNOS), neuronal (nNOS), and inducible (iNOS) NOS expression were measured in the renal cortex and medulla. In vitro, ANP-induced renal NOS activity was determined in the presence of iNOS and nNOS inhibitors, NPR-A/B blockers, guanine nucleotide-regulatory (G(i)) protein, and calmodulin inhibitors. Renal NOS activity was higher in SHR than in WKY. ANP increased NOS activity, but activation was lower in SHR than in WKY. ANP had no effect on expression of NOS isoforms. ANP-induced NOS activity was not modified by iNOS and nNOS inhibitors. NPR-A/B blockade blunted NOS stimulation via ANP in kidney. The renal NOS response to ANP was reduced by G(i) protein and calmodulin inhibitors. We conclude that ANP interacts with NPR-C, activating Ca-calmodulin eNOS through G(i) protein. NOS activation also involves NPR-A/B. The NOS response to ANP was diminished in kidneys of SHR. The impaired NO system response to ANP in SHR participates in the maintenance of high blood pressure.
authors.affiliation: Cátedra de Fisiología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, IQUIMEFA-CONICET, BuenosAires, Argentina.
authors.forename: Rosana
authors.initials: R
authors.lastname: Elesgaray
authors.forename: Carolina
authors.initials: C
authors.lastname: Caniffi
authors.forename: Lucía
authors.initials: L
authors.lastname: Savignano
authors.forename: Mariana
authors.initials: M
authors.lastname: Romero
authors.forename: Myriam
authors.initials: M
authors.lastname: Mac Laughlin
authors.forename: Cristina
authors.initials: C
authors.lastname: Arranz
authors.forename: María A
authors.initials: MA
authors.lastname: Costa
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D004231:Diuresis / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism; D007668:Kidney / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D007677:Kidney Function Tests; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009318:Natriuresis / Q000187:drug effects; D009566:Nitrates / Q000652:urine; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009573:Nitrites / Q000652:urine; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D009320:Atrial Natriuretic Factor; D019001:Nitric Oxide Synthase; D017461:Receptors, Atrial Natriuretic Factor; D019331:NG-Nitroarginine Methyl Ester