title: Cardiovascular and renal responses produced by central orphanin FQ/nociceptin occur independent of renal nerves.
abstract: The present study investigated the role of the renal nerves in mediating the cardiovascular and renal responses produced by the central administration of the opioid-like peptide orphanin FQ/nociceptin (OFQ/N) in conscious Sprague-Dawley rats. In conscious rats, OFQ/N (10 microgram icv) produced a transient bradycardia and hypotension (nadir 20 min). Although renal sympathetic nerve activity (RSNA) initially remained unchanged, a delayed renal sympathoinhibitory response occurred after recovery (30 min) of blood pressure. By 30 and 70 min postinjection, RSNA decreased to 75 and 66% of control, respectively. Coinciding with the decrease in RSNA, central OFQ/N elicited a diuresis and antinatriuresis that occurred independent of changes in renal hemodynamics. In other studies, intracerebroventricular OFQ/N produced similar cardiovascular and renal excretory responses in bilaterally renal-denervated rats. Finally, in conscious sinoaortic deafferentiated rats, intracerebroventricular OFQ/N produced a rapid decrease in RSNA (55% of control, 10 min; 38% of control, 20 min) that paralleled the onset of the hypotension and bradycardia. These studies demonstrate that in conscious rats, intracerebroventricular OFQ/N produces a centrally mediated inhibition of RSNA which, due to activation of baroreflex mechanisms, is temporally dissociated from the hypotensive and bradycardia responses. As revealed in renal-denervated rats, the cardiovascular and renal excretory responses produced by central OFQ/N occur by a pathway that is independent of intact renal nerves or changes in renal hemodynamics.
authors.affiliation: Department of Pharmacology Louisiana State University Medical Center, New Orleans, Louisiana 70112, USA. dkapus@lsumc.edu
authors.forename: D R
authors.initials: DR
authors.lastname: Kapusta
authors.forename: V A
authors.initials: VA
authors.lastname: Kenigs
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000502:physiology*; D002320:Cardiovascular Physiological Phenomena; D002319:Cardiovascular System / Q000187:drug effects*; D004338:Drug Combinations; D006339:Heart Rate / Q000187:drug effects; D007276:Injections, Intraventricular; D007668:Kidney / Q000187:drug effects* / Q000294:innervation / Q000502:physiology*; D008297:Male; D009433:Neural Inhibition; D018847:Opioid Peptides / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology*; D000097629:Nociceptin
chemical_list: D004338:Drug Combinations; D018847:Opioid Peptides; D014665:Vasodilator Agents; D000097629:Nociceptin