title: Possible mechanism(s) for relaxant effect of aqueous and macerated extracts from Nigella sativa on tracheal chains of guinea pig.
abstract: BACKGROUND
  In previous studies, the relaxant, anticholinergic (functional antagonism) and antihistaminic effects of Nigella sativa have been demonstrated on guinea pig tracheal chains. To elucidate the other mechanisms responsible for the relaxant effect of this plant, its inhibitory effect on the calcium channel was examined in this study.
  
  
  RESULTS
  The inhibitory effects of both concentrations of diltiazem in all three groups of experiments were significantly greater than those of saline (p < 0.01 to P < 0.001). The inhibitory of two larger concentrations of aqueous extracts in group 1 and 2 were significantly greater than those of saline (p < 0.01 to P < 0.001). The effect of two larger concentrations of macerated extract in group 1 and all concentrations of this extract in group 2 were also significantly greater than those of saline (p < 0.01 to P < 0.001). However, the extract of Nigella sativa did not show any inhibitory effect in group 3. There was a significant correlation between inhibitory effect and increasing concentrations for both extracts and diltiazem in groups 1 and 2 (p < 0.05 to p < 0.005).
  
  
  CONCLUSIONS
  Although the extracts of Nigella sativa showed inhibitory effects on pre-contracted tracheal chains in the presence of both ordinary and calcium free Krebs solution, the absence of inhibitory effects of the extracts on KCl induced contraction of tracheal chains suggest that the calcium channel blocking effect of this plant dose not contribute to the relaxant effect of this plant on the tracheal chains of guinea pigs.
authors.affiliation: Dept. of Physiology, Ghaem Medical Centre, Mashhad University of Medical Sciences, Mashhad, Iran. mhboskabady@hotmail.com
authors.forename: Mohammad H
authors.initials: MH
authors.lastname: Boskabady
authors.forename: Batool
authors.initials: B
authors.lastname: Shirmohammadi
authors.forename: Parastoo
authors.initials: P
authors.lastname: Jandaghi
authors.forename: Sahar
authors.initials: S
authors.lastname: Kiani
mesh_terms: D000818:Animals; D001993:Bronchodilator Agents / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D004110:Diltiazem / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects*; D031881:Nigella sativa / Q000737:chemistry*; D010936:Plant Extracts / Q000494:pharmacology; D010946:Plants, Medicinal; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects* / Q000502:physiology; D014867:Water
chemical_list: D001993:Bronchodilator Agents; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010936:Plant Extracts; D015221:Potassium Channels; D014867:Water; D011189:Potassium Chloride; D004110:Diltiazem