title: Role of catalase in the smooth muscle relaxant actions of sodium azide and cyanamide.
abstract: The aim of this study was to determine the role of catalase in the smooth muscle relaxant actions of sodium azide and cyanamide. The effects of 3-amino-1,2,4-triazole suggested a role for this enzyme in the relaxant actions of sodium azide on rat aorta and bovine retractor penis muscle and cyanamide on rat aorta. Moreover, results obtained using a difference spectrophotometric assay based upon the oxidation of haemoglobin were consistent with the catalase-dependent oxidation of sodium azide to nitric oxide (NO) and of cyanamide to nitroxyl anion. Surprisingly, however, no free nitric oxide or nitroxyl was detected in solution using a sensitive electrode. This anomaly might be explained if the stable complexes of catalase with nitric oxide or nitroxyl do not release their respective ligand except to sites of high affinity, such as the haemoglobin employed in the difference spectrophotometric assay, or indeed, the soluble guanylate cyclase within the smooth muscle.
authors.affiliation: Division of Neuroscience and Biomedical Systems, Institute of Biomedical and Life Sciences, West Medical Building, University of Glasgow, G12 8QQ, Glasgow, UK.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Shahidullah
authors.forename: Andrew
authors.initials: A
authors.lastname: Duncan
authors.forename: Peter D
authors.initials: PD
authors.lastname: Strachan
authors.forename: Komel M
authors.initials: KM
authors.lastname: Rafique
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Ball
authors.forename: Mark J W
authors.initials: MJ
authors.lastname: McPate
authors.forename: Silvia
authors.initials: S
authors.lastname: Nelli
authors.forename: William
authors.initials: W
authors.lastname: Martin
mesh_terms: D000640:Amitrole / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D002374:Catalase / Q000502:physiology*; D002417:Cattle; D003484:Cyanamide / Q000633:toxicity*; D004563:Electrochemistry; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006454:Hemoglobins / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism / Q000502:physiology; D009573:Nitrites / Q000494:pharmacology; D009589:Nitrogen Oxides / Q000378:metabolism; D010069:Oxadiazoles / Q000494:pharmacology; D010413:Penis / Q000187:drug effects* / Q000502:physiology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D019810:Sodium Azide / Q000633:toxicity*; D013053:Spectrophotometry
chemical_list: C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D004791:Enzyme Inhibitors; D006454:Hemoglobins; D009573:Nitrites; D009589:Nitrogen Oxides; D010069:Oxadiazoles; D011810:Quinoxalines; C021229:oxyhyponitrite; D009569:Nitric Oxide; D003484:Cyanamide; D019810:Sodium Azide; D002374:Catalase; C039900:nitroxyl; D000640:Amitrole