title: Hypotensive effect of Gentiana floribunda is mediated through Ca++ antagonism pathway.
abstract: BACKGROUND
  Gentiana floribunda was investigated for the possible hypotensive and vasodilator activities in an attempt to rationalize its traditional use in hypertension.
  
  
  METHODS
  The crude extract of Gentiana floribunda (Gf.Cr) was studied in anaesthetized rats and isolated thoracic aorta tissues.
  
  
  RESULTS
  Gf.Cr which tested positive for presence of flavonoids, saponins, sterols, tannins and terpenes caused dose-dependent (3.0-100 mg/kg) fall in arterial blood pressure (BP) of rats under anaesthesia. In rat aortic ring preparations denuded of endothelium, Gf.Cr at concentration range of 1.0-10 mg/mL relaxed high K+ (80 mM) and phenylephrine (PE, 1 μM)-induced contractions and shifted Ca++ dose-response curves to right, similar to that caused by verapamil. It also suppressed PE (1 μM) control peak responses at 0.3-1.0 mg/mL, obtained in Ca++-free medium, as exhibited by verapamil. Pre-treatment of tissues with Gf.Cr produced rightward non-parallel shift of PE-curves with decline of maximum contractile response. The vasodilator effect of Gf.Cr was endothelial-independent, as it was not blocked by Nω-nitro-L-arginine methyl ester hydrochloride, atropine and indomethacin in endothelium-intact aortic tissues.
  
  
  CONCLUSIONS
  These data indicate that BP-lowering action of Gentiana floribunda occurred via Ca++ antagonism (inhibition of Ca++ ingress and release from intracellular stores), which provides pharmacological basis to justify its effectiveness in hypertension.
authors.affiliation: Centre for Natural Products Research and Drug Discovery, Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia. arifullahkhan979@hotmail.com
authors.forename: Arif-ullah
authors.initials: AU
authors.lastname: Khan
authors.forename: Mohamad Rais
authors.initials: MR
authors.lastname: Mustafa
authors.forename: Asif Ullah
authors.initials: AU
authors.lastname: Khan
authors.forename: Dharmani Devi
authors.initials: DD
authors.lastname: Murugan
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001013:Aorta, Thoracic; D001120:Arginine / Q000031:analogs & derivatives; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D002317:Cardiovascular Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular; D030012:Gentiana / Q000737:chemistry*; D006973:Hypertension / Q000188:drug therapy* / Q000378:metabolism; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D010656:Phenylephrine; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D011188:Potassium; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D014661:Vasoconstriction / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology / Q000627:therapeutic use*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D000959:Antihypertensive Agents; D002317:Cardiovascular Agents; D010936:Plant Extracts; D014665:Vasodilator Agents; D010656:Phenylephrine; C026512:arginine methyl ester; D001285:Atropine; D001120:Arginine; D014700:Verapamil; D011188:Potassium; D002118:Calcium; D007213:Indomethacin