title: Endothelium-independent vasorelaxant effects of hydroalcoholic extract from Nigella sativa seed in rat aorta: the roles of Ca2+ and K+ channels.
abstract: OBJECTIVE
  The aim of this study was to elucidate the mechanism(s) responsible for the vasorelaxant effect of Nigella sativa (N. sativa).
  
  
  METHODS
  The activity of different concentrations of N. sativa extract was evaluated on contractile responses of isolated aorta to KCl and phenylephrine (PE).
  
  
  RESULTS
  The extract (2-14 mg/mL) induced a concentration dependent relaxation both in endothelium-intact and endothelium-denuded aortic rings precontracted by PE (10(-6) M) and KCl (6 × 10(-2) M). Extract reduced PE- and KCl-induced contractions in presence of cumulative concentrations of calcium (10(-5)-10(-2) M) significantly. L-NAME and indomethacin had no effect on vasorelaxation effect of extract in PE-induced contraction. Diltiazem and heparin reduced significantly this vasorelaxation at a concentration of 14 mg/mL of extract; however, N. sativa-induced relaxation was not affected by ruthenium red. Tetraethylammonium chloride reduced the extract-induced relaxation in concentrations of 2-6 mg/mL of extract significantly but glibenclamide reduced this relaxative effect in all concentrations of extract.
  
  
  CONCLUSIONS
  The inhibitory effect of N. sativa seed extract on the contraction induced by PE and KCl was endothelium-independent. This relaxation was mediated mainly through the inhibition of Ca(2+) and KATP channels and also intracellular calcium release.
authors.affiliation: Cardiovascular Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad 9177948564, Iran ; Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad 9177948564, Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Niazmand
authors.affiliation: Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad 9177948564, Iran.
authors.forename: Elahe
authors.initials: E
authors.lastname: Fereidouni
authors.affiliation: Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad 9177948564, Iran ; Neurogenic Inflammation Research Centre, School of Medicine, Mashhad University of Medical Sciences, Mashhad 9177948564, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Mahmoudabady
authors.affiliation: Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad 9177948564, Iran.
authors.forename: Seyed Mojtaba
authors.initials: SM
authors.lastname: Mousavi
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D009119:Muscle Contraction / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000378:metabolism; D031881:Nigella sativa / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D015221:Potassium Channels / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012639:Seeds / Q000737:chemistry*; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000493:pharmacokinetics
chemical_list: D015220:Calcium Channels; D010936:Plant Extracts; D015221:Potassium Channels; D014665:Vasodilator Agents; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester