title: Cinnamaldehyde induces endothelium-dependent and -independent vasorelaxant action on isolated rat aorta.
abstract: The vasorelaxant effect of cinnamaldehyde, one of the major oil components in Cinnamomi Cortex, was studied using isolated rat aorta. Cinnamaldehyde at final concentrations of 1 microM to 1 mM showed dose-dependent relaxation of the rat aorta contracted by treatment with prostaglandin F2alpha, norepinephrine or KCl. In addition, cinnamaldehyde relaxed prostaglandin F2alpha-precontracted aortic rings with endothelium and without endothelium, with the latter being significantly less sensitive than the former. Relaxation induced by cinnamaldehyde with endothelium was significantly inhibited by NG-nitro-L-arginine methyl ester (L-NAME), while nonselective cyclooxygenase inhibitor (indomethacin), beta-adrenergic receptor blocker (propranolol), an inhibitor of phosphodiesterase (theophylline), a delayed rectifier K+ channel blocker (tetraethyl ammonium chloride), or an ATP-sensitive K+ channel blocker (glibenclamide) did not reduce the relaxation induced by cinnamaldehyde with endothelium treated by L-NAME. Conversely, aorta pretreatment with L-NAME and theophylline increased the relaxation by cinnamaldehyde significantly compared to aorta pretreatment with only L-NAME. Furthermore, cinnamaldehyde significantly inhibited Ca2+-induced contraction. These results suggested that the vasorelaxant effects of cinnamaldehyde were derived from both endothelium-dependent and -independent effects. Endothelium-dependent relaxation is affected by nitric oxide, and one of the mechanisms of endothelium-independent relaxation is thought to be influenced by the blocking of Ca2+ channels.
authors.affiliation: Department of Kampo Diagnostics, Institute of Natural Medicine, University of Toyama, Japan.
authors.forename: Ayano
authors.initials: A
authors.lastname: Yanaga
authors.forename: Hirozo
authors.initials: H
authors.lastname: Goto
authors.forename: Takako
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Hikiami
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Shibahara
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Shimada
mesh_terms: D000171:Acrolein / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D000171:Acrolein; C012843:cinnamaldehyde; D019331:NG-Nitroarginine Methyl Ester