Pan Zhenwei, Feng Tieming, Shan Luchen, Cai Benzhi, Chu Wenfeng, Niu Huili, Lu Yanjie, Yang Baofeng
Department of Pharmacology, Harbin Medical University, P. R. China.
Phytother Res. 2008 Nov;22(11):1428-33. doi: 10.1002/ptr.2364.
Scutellarin is a flavonoid extracted from the traditional Chinese herb, Erigeron breviscapus Hand Mazz. In the present study, the vasorelaxant effects of scutellarin and the underlying mechanism were investigated in isolated rat aorta. Scutellarin (3, 10, 30, 100 microm) caused a dose-dependent relaxation in both endothelium-intact and endothelium-denuded rat aortic rings precontracted with noradrenaline bitartrate (IC(50) = 7.7 +/- 0.6 microm), but not with potassium chloride. Tetraethylammonium, glibenclamide, atropine, propranolol, indomethacin and N(G)-nitro-l-arginine methyl ester had no influence on the vasorelaxant effect of scutellarin, which further excluded the involvement of potassium channels, muscarinic receptor, nitric oxide pathway and prostaglandin in this effect. Pretreatment with scutellarin decreased the tonic phase, but not the phasic phase of the noradrenaline bitartrate induced tension increment. Scutellarin also alleviated Ca(2+)-induced vasoconstriction in Ca(2+)-depleted/noradrenaline bitartrate pretreated rings in the presence of voltage-dependent calcium channel blocker verapamil. The noradrenaline bitartrate evoked intracellular calcium increase was inhibited by scutellarin. Scutellarin had no effect on phorbol-12,13-diacetate induced contraction in a calcium-free bath solution. These results showed that scutellarin could relax thoracic artery rings in an endothelium-independent manner. The mechanism seems to be the inhibition of extracellular calcium influx independent of the voltage-dependent calcium channel.
灯盏花素是从传统中药短葶飞蓬（Erigeron breviscapus Hand Mazz.）中提取的一种黄酮类化合物。在本研究中，我们在离体大鼠主动脉中研究了灯盏花素的血管舒张作用及其潜在机制。灯盏花素（3、10、30、100微摩尔）可使预先用重酒石酸去甲肾上腺素预收缩的完整内皮和去内皮大鼠主动脉环产生剂量依赖性舒张（IC50 = 7.7±0.6微摩尔），但对氯化钾预收缩的主动脉环无此作用。四乙铵、格列本脲、阿托品、普萘洛尔、吲哚美辛和N(G)-硝基-L-精氨酸甲酯对灯盏花素的血管舒张作用无影响，这进一步排除了钾通道、毒蕈碱受体、一氧化氮途径和前列腺素参与此作用。灯盏花素预处理可降低重酒石酸去甲肾上腺素诱导的张力增加的强直相，但不影响其相性相。在电压依赖性钙通道阻滞剂维拉帕米存在的情况下，灯盏花素还可减轻钙耗尽/重酒石酸去甲肾上腺素预处理环中钙诱导的血管收缩。灯盏花素可抑制重酒石酸去甲肾上腺素引起的细胞内钙增加。在无钙浴溶液中，灯盏花素对佛波醇-12,13-二乙酸酯诱导的收缩无影响。这些结果表明，灯盏花素可通过非内皮依赖方式舒张胸主动脉环。其机制似乎是抑制细胞外钙内流，且不依赖于电压依赖性钙通道。
