title: Cardiovascular effects of eugenol, a phenolic compound present in many plant essential oils, in normotensive rats.
abstract: Cardiovascular effects of intravenous (i.v.) treatment with eugenol (Eug), a natural pungent present in many plant essential oils, were investigated in normotensive rats. In either anesthetized or conscious rats, i.v. bolus injections of Eug (1 to 10 mg/kg) elicited immediate and dose-dependent hypotension and bradycardia. Magnitude of Eug-induced hypotension was similar in both groups. Pretreatment of anesthetized rats with bilateral vagotomy almost abolished the bradycardic responses to Eug without affecting the hypotension. Likewise, i.v. pretreatment of conscious rats with methylatropine (1 mg/kg) or hexamethonium (30 mg/kg) significantly reduced the Eug-induced bradycardia without affecting the hypotension. However, i.v. pretreatment with the nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl (L-NAME, 20 mg/kg), affected neither the hypotension nor the bradycardia elicited by Eug. In rat mesenteric bed preparations precontracted with potassium (60 mM), Eug (0.1-2 mM) induced a reversible and concentration-dependent vasodilator effect, which remained unaffected by atropine (1 microM). These results show that i.v. treatment of rats with Eug induces dose-dependent hypotension and bradycardia, which occurred independently. The bradycardia appears dependent upon the presence of an intact and functional parasympathetic nerve drive to the heart while the hypotension is due to an active vascular relaxation rather than withdrawal of sympathetic tone. Released nitric oxide from vascular endothelial cells seems to be not involved in the mediation of Eug-induced hypotension.
authors.affiliation: Department of Physiology and Pharmacology, Federal University of Pernambuco, Recife, Brazil. lahlou@ufpe.br
authors.forename: Saad
authors.initials: S
authors.lastname: Lahlou
authors.forename: Leylliane Fátima Leal
authors.initials: LF
authors.lastname: Interaminense
authors.forename: Pedro Jorge Caldas
authors.initials: PJ
authors.lastname: Magalhães
authors.forename: José Henrique
authors.initials: JH
authors.lastname: Leal-Cardoso
authors.forename: Gloria Pinto
authors.initials: GP
authors.lastname: Duarte
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D001919:Bradycardia / Q000139:chemically induced*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005054:Eugenol / Q000008:administration & dosage / Q000633:toxicity*; D006339:Heart Rate / Q000187:drug effects; D007022:Hypotension / Q000139:chemically induced*; D007275:Injections, Intravenous; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D010938:Plant Oils / Q000008:administration & dosage / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar
chemical_list: D004791:Enzyme Inhibitors; D010938:Plant Oils; D005054:Eugenol; D019331:NG-Nitroarginine Methyl Ester