title: The role of nitric oxide in the regulation of the systemic and pulmonary vasculature of the rattlesnake, Crotalus durissus terrificus.
abstract: The functional role of nitric oxide (NO) was investigated in the systemic and pulmonary circulations of the South American rattlesnake, Crotalus durissus terrificus. Bolus, intra-arterial injections of the NO donor, sodium nitroprusside (SNP) caused a significant systemic vasodilatation resulting in a reduction in systemic resistance (Rsys). This response was accompanied by a significant decrease in systemic pressure and a rise in systemic blood flow. Pulmonary resistance (Rpul) remained constant while pulmonary pressure (Ppul) and pulmonary blood flow (Qpul) decreased. Injection of L-Arginine (L-Arg) produced a similar response to SNP in the systemic circulation, inducing an immediate systemic vasodilatation, while Rpul was unaffected. Blockade of NO synthesis via the nitric oxide synthase inhibitor, L-NAME, did not affect haemodynamic variables in the systemic circulation, indicating a small contribution of NO to the basal regulation of systemic vascular resistance. Similarly, Rpul and Qpul remained unchanged, although there was a significant rise in Ppul. Via injection of SNP, this study clearly demonstrates that NO causes a systemic vasodilatation in the rattlesnake, indicating that NO may contribute in the regulation of systemic vascular resistance. In contrast, the pulmonary vasculature seems far less responsive to NO.
authors.affiliation: Departamento de Zoologia, Centro de Aquicultura, UNESP, Caixa Postal, 199, 13506-907 Rio Claro, Brazil.
authors.forename: Gina L J
authors.initials: GL
authors.lastname: Galli
authors.forename: Nini
authors.initials: N
authors.lastname: Skovgaard
authors.forename: Augusto S
authors.initials: AS
authors.lastname: Abe
authors.forename: Edwin W
authors.initials: EW
authors.lastname: Taylor
authors.forename: Tobias
authors.initials: T
authors.lastname: Wang
mesh_terms: D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001158:Arteries / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D017839:Crotalus / Q000097:blood / Q000502:physiology*; D004837:Epinephrine / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D011652:Pulmonary Circulation / Q000502:physiology*; D012039:Regional Blood Flow / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
chemical_list: D009599:Nitroprusside; D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester; D004837:Epinephrine
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