Naseri Mohammad Kazem Gharib, Arabian Maedeh, Badavi Mohammad, Ahangarpour Akram
Physiology Research Center, Department of Physiology, School of Medicine, Ahwaz Jundishapur University of Medical Sciences, P.O. Box 61335-189, Ahwaz, Iran.
Pak J Biol Sci. 2008 Jun 15;11(12):1569-75. doi: 10.3923/pjbs.2008.1569.1575.
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.
本研究旨在探讨洋葱（葱属）皮水醇提取物（OPE）对高果糖饮食诱导的大鼠高血压及主动脉收缩性的影响。OPE采用浸渍法用70%乙醇制备。从成年雄性大鼠（Wistar）分离胸主动脉，在1 g静息张力下悬于Krebs-Henseleit溶液中。用氯化钾（80 mM）或去氧肾上腺素（Phe，1 μM）使组织制备物收缩，然后累积加入提取物（0.0625 - 2 mg mL⁻¹）。通过在饮用水中添加果糖（10% W/V）6周诱导阴性对照组和三组大鼠高血压，但对照组饮用自来水。高血压组在最后3周通过灌胃每天给予生理盐水或200、400和800 mg kg⁻¹的OPE。结果表明，OPE以浓度依赖方式降低氯化钾或Phe诱导的主动脉收缩（p < 0.001）。去除主动脉内皮并未减弱OPE的活性。分别用L - 硝基精氨酸甲酯（100 μM）、亚甲蓝（10 μM）和吲哚美辛（10 μM）抑制一氧化氮、环鸟苷酸和前列腺素合成并未减弱OPE的活性。阿托品消除了乙酰胆碱诱导的Phe预收缩主动脉的舒张，但未消除OPE诱导的舒张。尽管提取物未改变心率，但3周后降低了果糖诱导的高血压（p < 0.001）。目前结果表明，OPE可能通过抑制钙内流降低主动脉收缩，但不涉及一氧化氮、环鸟苷酸、内皮和前列腺素。OPE的降压作用可能归因于提取物中的槲皮素含量、抗氧化活性以及抑制血管平滑肌细胞钙内流。
