title: Cardiovascular responses to ATP microinjected into the paraventricular nucleus are mediated by nitric oxide and NMDA glutamate receptors in awake rats.
abstract: We hypothesize that a local ATP-NO-NMDA glutamate receptor interaction in the paraventricular nucleus (PVN) modulates the baseline mean arterial pressure and heart rate in unanaesthetized rats. The microinjection of α,β-methylene ATP [methyl ATP; 0.06, 0.12 and 1.2 nmol (100 nl)(-1)] into the PVN caused pressor and tachycardiac responses. Cardiovascular responses evoked by methyl ATP [0.12 nmol (100 nl)(-1)] in the PVN were blocked by pretreatment with the ganglion blocker pentolinium (5 mg kg(-1) i.v.). Also, responses to the injection of methyl ATP [0.12 nmol (100 nl)(-1)] into the PVN were reduced by pretreatment with the selective P2 purinergic receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid [0.5 nmol (100 nl)(-1)], the neuronal NO synthase inhibitor N(ω)-propyl-l-arginine [0.04 nmol (100 nl)(-1)] or the selective NMDA glutamate receptor antagonist LY235959 [2 nmol (100 nl)(-1)]. In addition, an injection of the NO donor sodium nitroprusside [27 nmol (100 nl)(-1)] into the PVN caused similar cardiovascular responses to those observed after methyl ATP, which were blocked by local pretreatment with LY235959. Therefore, the present results suggest that cardiovascular responses evoked by methyl ATP in the PVN involve a local production of NO, which promotes local glutamate release and activation of NMDA receptors that are probably located in pre-autonomic parvocellular neurons, leading to sympathetic nervous system stimulation.
authors.affiliation: C. Busnardo: Department of Pharmacology, School of Medicine of Ribeirão Preto, USP, Av. Bandeirantes 3900, 14049-900, Ribeirão Preto, São Paulo, Brazil. crisbus@usp.br.
authors.forename: Cristiane
authors.initials: C
authors.lastname: Busnardo
authors.forename: Nilson C
authors.initials: NC
authors.lastname: Ferreira-Junior
authors.forename: Josiane C
authors.initials: JC
authors.lastname: Cruz
authors.forename: Benedito H
authors.initials: BH
authors.lastname: Machado
authors.forename: Fernando M A
authors.initials: FM
authors.lastname: Correa
authors.forename: Leonardo B M
authors.initials: LB
authors.lastname: Resstel
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D005730:Ganglionic Blockers / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D008845:Microinjections; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects*; D058919:Purinergic P2 Receptor Antagonists / Q000494:pharmacology; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D052999:Quinazolinones; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D014851:Wakefulness
chemical_list: C435663:2-(2-(5-bromo-1H-indol-3-yl)ethyl)-3-(1-methylethoxyphenyl)-4-(3H)-quinazolinone; D005730:Ganglionic Blockers; C109599:N(omega)-propylarginine; D058919:Purinergic P2 Receptor Antagonists; D052999:Quinazolinones; D016194:Receptors, N-Methyl-D-Aspartate; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D009599:Nitroprusside; D009569:Nitric Oxide; D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; D001120:Arginine; C002630:alpha,beta-methyleneadenosine 5'-triphosphate