title: Role of brain nitric oxide in the cardiovascular control of bullfrogs.
abstract: The goal of the present study was to determine if nitric oxide (NO) acting on the brain of bullfrog (Lithobates catesbeianus) is involved in arterial pressure and heart rate (HR) control by influencing sympathetic activity. We investigated the effect of intracerebroventricular injections of L-NMMA (a nonselective NO synthase inhibitor) on mean arterial blood pressure (MAP), HR and cutaneous vascular conductance (CVC) of pelvic skin after intravenous injection of α or β adrenergic blockers, prazosin or sotalol, respectively. Arterial pressure was directly measured by a telemetry sensor inserted in the aortic arch of animals. L-NMMA increased MAP, but did not change HR. This hypertensive response was inhibited by the pre-treatment with prazosin, but accentuated by sotalol. The effect of L-NMMA on MAP was also inhibited by i.v. injections of the ganglionic blocker, hexamethonium. Thus, NO acting on the brain of bullfrog seems to present a hypotensive effect influencing the sympathetic activity dependent on α and β adrenergic receptors in the periphery.
authors.affiliation: Department of Animal Morphology and Physiology, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo 14884-900, Brazil.
authors.forename: Lucas A
authors.initials: LA
authors.lastname: Zena
authors.forename: Luciane H
authors.initials: LH
authors.lastname: Gargaglioni
authors.forename: Kênia C
authors.initials: KC
authors.lastname: Bícego
mesh_terms: D058668:Adrenergic alpha-1 Receptor Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000378:metabolism / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism / Q000502:physiology*; D011224:Prazosin / Q000008:administration & dosage / Q000494:pharmacology; D011892:Rana catesbeiana / Q000378:metabolism / Q000502:physiology*; D012867:Skin / Q000098:blood supply / Q000187:drug effects; D013015:Sotalol / Q000008:administration & dosage / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D058668:Adrenergic alpha-1 Receptor Antagonists; D000319:Adrenergic beta-Antagonists; D004791:Enzyme Inhibitors; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D013015:Sotalol; D011224:Prazosin