title: Nociceptin/orphanin FQ increases blood pressure and heart rate via sympathetic activation in sheep.
abstract: This study was undertaken to examine the cardiovascular effects of nociceptin/Orphanin FQ (OFQ). Nociceptin/OFQ (10-300 nmol/kg, IV) stimulates an increase in mean blood pressure (MBP) and heart rate (HR) in chronically catheterized sheep. Pretreatment with phenoxybenzamine (5 mg/kg) attenuated the pressor response, consistent with sympathetically mediated vasoconstriction. Furthermore, the lack of a reflex bradycardia suggests either blunting of the baroreflex by nociceptin/OFQ or direct beta-adrenergic activation. The bradycardic response to norepinephrine (0.6 microg/kg, IV) remained intact after nociceptin/OFQ administration, demonstrating that nociceptin/OFQ does not blunt the baroreflex. Additionally, the increase in HR was completely reversed by pretreatment with propranolol. These data suggest that nociceptin/OFQ plays a role in cardiovascular regulation via sympathetic activation.
authors.affiliation: Department of Pharmacology, Cornell University Medical College, New York, NY 10021, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Arndt
authors.forename: D
authors.initials: D
authors.lastname: Wu
authors.forename: Y
authors.initials: Y
authors.lastname: Soong
authors.forename: H H
authors.initials: HH
authors.lastname: Szeto
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002408:Catheters, Indwelling; D004336:Drug Antagonism; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D007262:Infusions, Intravenous; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D018847:Opioid Peptides / Q000494:pharmacology*; D010643:Phenoxybenzamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D012756:Sheep; D013564:Sympathetic Nervous System / Q000187:drug effects*; D013565:Sympatholytics / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D014851:Wakefulness; D000097629:Nociceptin
chemical_list: D000319:Adrenergic beta-Antagonists; D009270:Naloxone; D009292:Narcotic Antagonists; D018847:Opioid Peptides; D010643:Phenoxybenzamine; D011433:Propranolol; D013565:Sympatholytics; D014665:Vasodilator Agents; D000097629:Nociceptin