title: Vasorelaxant and hypotensive effects of Allium cepa peel hydroalcoholic extract in rat.
abstract: The aim of present study was to investigate the effect of onion (Allium cepa) peel hydroalcoholic extract (OPE) on rat hypertension induced by high-fructose diet and aorta contractility. The OPE was prepared by maceration method using 70% ethanol. The thoracic aorta from male adult rat (Wistar) was dissected and suspended in Krebs-Henseleit solution under 1 g resting tension. Tissue preparation was contracted by KCl (80 mM) or phenylephrine (Phe, 1 microM) and then the extract was applied cumulatively (0.0625-2 mg mL(-1)). Hypertension was induced in negative control and three groups of rats by adding fructose (10% WN/V) in drinking water for 6 weeks but control group received tap water. Hypertensive groups received saline or OPE at 200, 400 and 800 mg kg(-1) daily for last 3 weeks by gavage. Results showed that OPE reduces aorta contractions induced by KCl or Phe in a concentration-dependent manner (p < 0.001). Removing aorta endothelium did not attenuate the OPE activity. Inhibition of nitric oxide, cGMP and prostaglandin synthesis by L-NAME (100 microM), methylene blue (10 microM) and indomethacin (10 microM), respectively, did not attenuate OPE activity. Atropine abolished ACh-induced relaxation in Phe precontracted aorta but not the OPE-induced relaxation. Although the extract did not change heart rate but after 3 weeks reduced the hypertension induced by fructose (p < 0.001). Present results indicated that OPE reduces aortic contractions possibly via inhibition of calcium influx but without involving NO, cGMP, endothelium and prostaglandins. The OPE hypotensive effect could be due to extract quercetin content, antioxidant activity and inhibiting vascular smooth muscle cells Ca2+ influx.
authors.affiliation: Physiology Research Center, Department of Physiology, School of Medicine, Ahwaz Jundishapur University of Medical Sciences, P.O. Box 61335-189, Ahwaz, Iran.
authors.forename: Mohammad Kazem Gharib
authors.initials: MK
authors.lastname: Naseri
authors.forename: Maedeh
authors.initials: M
authors.lastname: Arabian
authors.forename: Mohammad
authors.initials: M
authors.lastname: Badavi
authors.forename: Akram
authors.initials: A
authors.lastname: Ahangarpour
mesh_terms: D000438:Alcohols / Q000378:metabolism*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007022:Hypotension / Q000188:drug therapy; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019697:Onions / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D011453:Prostaglandins / Q000378:metabolism; D051381:Rats; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D000438:Alcohols; D010936:Plant Extracts; D011453:Prostaglandins; D014665:Vasodilator Agents; D011189:Potassium Chloride; D008751:Methylene Blue; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin