title: Mechanisms underlying the antihypertensive properties of Urtica dioica.
abstract: Urtica dioica has traditionally been used in the management of cardiovascular disorders especially hypertension. The aim of this study was to explore pharmacological base of its use in hypertension.
  
  
  
  Crude methanolic extract of U. dioica (Ud.Cr) and its fractions (Ud.EtAc, Ud.nHex, Ud.Chl and Ud.Aq) were tested in vivo on normotensive and hypertensive rats under anesthesia for blood pressure lowering effect. In-vitro experiments on rat and rabbit aortae were employed to probe the vasorelaxation mechanism(s). The responses were measured using pressure and force transducers connected to PowerLab Data Acquisition System.
  
  
  
  Ud.Cr and fractions were found more effective antihypertensive in hypertensive rats than normotensive with remarkable potency exhibited by the ethyl acetate fraction. The effect was same in the presence of atropine. In isolated rat aortic rings, Ud.Cr and all its fractions exhibited L-NAME sensitive endothelium-dependent vasodilator effect and also inhibit K(+) (80 mM)-induced pre-contractions. In isolated rabbit thoracic aortic rings Ud.Cr and its fractions induced relaxation with more potency against K(+) (80 mM) than phenylephrine (1 µM) like verapamil, showing Ud.EtAc fraction the most potent one. Pre-incubation of aortic rings with Ud.Cr and its fractions exhibited Ca(2+) channel blocking activity comparable with verapamil by shifting Ca(2+) concentration response curves to the right. Ud.Cr and its fractions also ablated the intracellular Ca(2+) release by suppressing PE peak formation in Ca(2+) free medium. When tested on basal tension, the crude extract and all fractions were devoid of any vasoconstrictor effect.
  
  
  
  These data indicate that crude methanolic extract and its fractions possess antihypertensive effect. Identification of NO-mediated vasorelaxation and calcium channel blocking effects explain the antihypertensive potential of U. dioica and provide a potential pharmacological base to its medicinal use in the management of hypertension.
authors: Department of Pharmacy, COMSATS Institute of Information Technology, University Road, Abbottabad, KPK, 22060, Pakistan.
authors: Rahila
authors: R
authors: Qayyum
authors: Department of Pharmacy, COMSATS Institute of Information Technology, University Road, Abbottabad, KPK, 22060, Pakistan.
authors: Hafiz Misbah-Ud-Din
authors: HM
authors: Qamar
authors: Department of Pharmacy, COMSATS Institute of Information Technology, University Road, Abbottabad, KPK, 22060, Pakistan.
authors: Shamim
authors: S
authors: Khan
authors: Department of Pharmacy, COMSATS Institute of Information Technology, University Road, Abbottabad, KPK, 22060, Pakistan.
authors: Umme
authors: U
authors: Salma
authors: Department of Pharmacy, COMSATS Institute of Information Technology, University Road, Abbottabad, KPK, 22060, Pakistan.
authors: Taous
authors: T
authors: Khan
authors: Department of Pharmacy, COMSATS Institute of Information Technology, University Road, Abbottabad, KPK, 22060, Pakistan. jabbarshah@ciit.net.pk.
authors: Abdul Jabbar
authors: AJ
authors: Shah
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D015220:Calcium Channels / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D011817:Rabbits; D017207:Rats, Sprague-Dawley; D026982:Urtica dioica / Q000737:chemistry*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D000959:Antihypertensive Agents; D015220:Calcium Channels; D010936:Plant Extracts; D014665:Vasodilator Agents; D000109:Acetylcholine; D009638:Norepinephrine
keywords: Antihypertensive; Endothelium-dependent and-independent; Urtica dioica; Vasorelaxant