土茯苓总黄酮对兔离体胸主动脉环的舒张作用及机制

Relaxing effect and mechanism of Smilax glabra flavonoids on isolated thoracic aorta rings of rabbits

目的探讨土茯苓总黄酮(SGF)对兔胸主动脉环的舒张作用及作用机制。方法制备内皮完整或去内皮的兔离体胸主动脉环并检验其内皮完整性,利用MedLab-U/8c生物信号采集处理系统检测药物刺激后血管张力。①内皮完整胸主动脉环分为氯化钾(KCl)60 mmol·L^(-1)、去氧肾上腺素(PE)1μmol·L^(-1)、去甲肾上腺素(NE)1μmol·L^(-1)、一氧化氮合酶抑制剂左旋硝基精氨酸甲酯(L-NAME)100μmol·L^(-1)和β2肾上腺素能受体阻滞剂ICI1185510.1μmol·L^(-1)组。KCl组、PE组和NE组分别预收缩胸主动脉环10 min,L-NAME组和ICI118551组分别预处理胸主动脉环30 min,并加入NE 1μmol·L^(-1)预收缩10 min。所有组间隔6 min加1次SGF,检测SGF 15.625~500 mg·L^(-1)浓度作用下血管张力;②去内皮胸主动脉环分为PE 1μmol·L^(-1)、NE 1μmol·L^(-1)和氯化钙(CaCl_(2))组。PE组和NE组预收缩胸主动脉环10 min,间隔6 min加1次SGF,检测SGF 15.625~250 mg·L^(-1)浓度作用下血管张力。CaCl_(2)组在无钙环境中加入KCl 60 mmol·L^(-1)预收缩胸主动脉环,同时加SGF 500 mg·L^(-1)预处理20 min,间隔6 min添加1次CaCl_(2),检测CaCl_(2)0.15~2.4 mmol·L^(-1)浓度作用下血管张力。同时设生理盐水组。结果在内皮存在条件下,SGF 15.625~250 mg·L^(-1)对KCl预收缩胸主动脉环无明显作用,而SGF 31.25~500 mg·L^(-1)对PE和NE预收缩胸主动脉环有显著舒张作用(P<0.01),最大舒张率分别达(56±12)%和(76±13)%。SGF 500 mg·L^(-1)对胸主动脉环的舒张功能减弱,舒张率为(40±10)%和(46±15)%。L-NAME 100μmol·L^(-1)预处理基本阻断SGF诱导的胸主动脉环舒张作用(P<0.01),而ICI1185510.1μmol·L^(-1)预处理仅部分阻断SGF的舒张效应(P<0.01)。去除胸主动脉环内皮后,SGF对PE和NE预收缩胸主动脉环无舒张作用,但SGF 500 mg·L^(-1)预处理能显著降低CaCl_(2)0.6~2.4 mmol·L^(-1)诱导的胸主动脉环收缩(P<0.05)。结论SGF可能具有一氧化氮依赖性诱导血管舒张、钙离子通道阻滞剂和β受体阻滞剂作用。

OBJECTIVE To investigate the effect of Smilax glabra flavonoids(SGF)on vasomotor function and the mechanism.METHODS Isolated rabbit thoracic aorta rings with intact or denuded endothelia were prepared and their integrity was verified.Changes in isometric tension were recorded with a MedLab-U/8c biological signal acquisition processing system.①Thoracic aortic rings with intact endothelia were grouped as follows:potassium chloride(KCl)60 mmol·L^(-1),phenylephrine(PE)1μmol·L^(-1),eorepinephrine(NE)1μmol·L^(-1),nitric oxide synthase inhibitor N-nitro-L-arginine-methyl-ester(L-NAME)100μmol·L^(-1)andβ2-adrenoceptor blocker(ICI118551)0.1μmol·L^(-1).The thoracic arterial rings were pre-contracted with KCl,PE and NE for 10 min,or pretreated with L-NAME and ICI118551 for 30 minutes before being pre-contracted with NE(1μmol·L^(-1))for 10 minutes,respectively.SGF was added to each group at an interval of 6 minutes,and the vascular tension was measured at the 15.625-500 mg·L^(-1)concentration of SGF.②Thoracic aortic rings with denuded endothelia were grouped as follows:PE 1μmol·L^(-1),NE 1μmol·L^(-1)and calcium chloride(CaCl_(2)).PE and NE were added to pre-contract thoracic aortic rings for 10 min,respectively.Then,SGF was added once every 6 min,and the changes of vascular tension were detected at the cumulative concentration of SGF 15.625-250 mg·L^(-1).In the CaCl_(2)group,KCl(60 mmol·L^(-1))was added to pre-contract the thoracic arterial rings in a calcium-free environment,and SGF(500 mg·L^(-1))was added for preconditioning for 20 minutes.CaCl_(2)was added every 6 min,and the vascular tension was detected at the concentration of CaCl_(2)(0.15-2.4 mmol·L^(-1)).A respective saline group was set up for each group at the same time.RESULTS SGF 15.625-250 mg·L^(-1)had no signifi⁃cant effect on KCl-pre-contracted thoracic arterial rings when the endothelia were intact while SGF 31.25-500 mg·L^(-1)could significantly relax both PE and NE pre-contracted thoracic arterial rings(P<0.01),whose maximum relaxation rate was(56±12)%and(76±13)%respectively.SGF 500 mg·L^(-1)could improve the diastolic function of the thoracic arterial rings,and the relaxation rate was(40±10)%and(46±15)%respectively.Pretreatment with L-NAME(100μmol·L^(-1))basically blocked SGF induced vasodilation(P<0.01),while ICI1185510.1μmol·L^(-1)pretreatment only partially blocked the relaxation effect of SGF(P<0.01).After removal of vascular endothelia,SGF had no relaxation effect on either PE or NE pre-contracted thoracic arterial rings,while SGF 500 mg·L^(-1)pretreatment could significantly reduce the contraction of thoracic arterial rings induced by CaCl_(2)0.6-2.4 mmol·L^(-1)(P<0.01).CONCLUSION SGF might be capable of NO-dependent vasodilation,calcium channel blocker,andβreceptor blocker.