title: Relaxant effect of 1-butanol fraction from Elaeagnus pungens leaf through inhibiting L-type Ca2+ channel on guinea pig tracheal smooth muscle.
abstract: BACKGROUND
  The leaf of Elaeagnus pungens thunb. (Family Elaeagnaceae) has been documented as an effective herb for the treatment of asthma and chronic bronchitis in traditional Chinese medicine. In the past years, only a few of preliminary studies reported the chemical constituents and pharmacology effects of the herb, but their action on the tracheal relaxation has not been investigated.
  
  
  OBJECTIVE
  To investigate the relaxing effect and mechanism of the extracts from Elaeagnus pungens leaves on guinea pig tracheal smooth muscle and bronchi smooth muscle cells.
  
  
  METHODS
  Four fractions of different polarities from Elaeagnus pungens leaves were tested to the tracheal strips on the resting tension or pre-contracted by histamine (20 μM) and acetylcholine (20 μM). Inhibitory effects of the 1-butanol fraction (400mg/ml) on cumulative histamine and acetylcholine (0.2-20 μM) induced contraction were measured. In order to determine the mediators on the 1-butanol fraction effect, the relaxing effect of the 1-butanol fraction was evaluated in the absence and presence of β-adrenoceptor antagonists (1 μM propranolol), K(+) channels-blockers (4-aminopyridine (2mM), tetraethylammonium chloride (5mM) or glibenclamide (10 μM)), the cyclooxygenase inhibitor (indomethacin, 10 μM), nitric oxide synthase inhibitor (Nω-nitro-L-arginine methyl ester, 100 μM) or L-type Ca(2+) channel inhibitor (nifedipine, 1 μM). Moreover, [Ca(2+)]i in bronchi smooth muscle cells was analyzed by measuring the fluorescence intensity with confocal system.
  
  
  RESULTS
  1-Butanol fraction induced the highest relaxant effect among four fractions of different polarities from Elaeagnus pungens leaves, and significantly relaxed the tracheal strip in the concentration-dependent manner on the resting tension and pre-contracted by histamine phosphate and acetylcholine. It also produced an unparallel rightward shift of the cumulative concentration-response curve of histamine or acetylcholine. Furthermore, the relaxant effect of 1-butanol fraction was not affected by propranolol, glibenclamide, tetraethylammonium chloride, 4-aminopyridine, indomethacin and Nω-nitro-L-arginine methyl ester. However, 1-butanol fraction-induced relaxation decreased after adding nifedipine. It also concentration-dependently inhibited CaCl2-induced contraction in the Ca(2+)-free, 60mM K(+)-containing solution. Additionally, [Ca(2+)]i in the BSMCs significantly reduced after administration of the 1-butanol fraction.
  
  
  CONCLUSIONS
  The 1-butanol fraction from Elaeagnus pungens leaves resulted in a relaxation in the non-precontracted and pre-contracted tracheal strips. The relaxant effect was not related to K(+) channels, NO, cGMP or β-adrenoceptors, but related to the inhibition of Ca(2+) influx through L-type Ca(2+) channels.
authors.affiliation: Institute for Ethical Medicine Research, College of Pharmacy, South-Central University for Nationalities, Minyuan Road 708, Hongshan District, Wuhan, Hubei, PR China.
authors.forename: Yue-bin
authors.initials: YB
authors.lastname: Ge
authors.forename: Qian
authors.initials: Q
authors.lastname: Dai
authors.forename: Ding-rong
authors.initials: DR
authors.lastname: Wan
authors.forename: Qing-hua
authors.initials: QH
authors.lastname: Liu
authors.forename: Zhi-nan
authors.initials: ZN
authors.lastname: Mei
mesh_terms: D020001:1-Butanol / Q000737:chemistry; D000818:Animals; D001980:Bronchi / Q000166:cytology; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000502:physiology*; D002478:Cells, Cultured; D031263:Elaeagnaceae; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves; D012997:Solvents / Q000737:chemistry; D014132:Trachea / Q000187:drug effects* / Q000502:physiology
chemical_list: D020746:Calcium Channels, L-Type; D010936:Plant Extracts; D012997:Solvents; D020001:1-Butanol; D002118:Calcium
keywords: 1-butanol fraction; Ca(2+) channels; Elaeagnus pungens leaf; Guinea pig tracheal smooth muscle; Relaxation