【作者】 许雷鸣；

【导师】 向继洲；

【作者基本信息】 华中科技大学 ， 药理学， 2006， 硕士

【摘要】 大麻是一种草本植物,民间以烟草吸入方式用其治疗疾病已有近千年的历史。大麻含有多种活性成分,在过去的20年内随着在分子水平上对这些化合物作用的研究,人们对大麻素类物质的医药价值有了新的重大发现。内源性大麻素类物质花生四烯乙醇胺(anandamide,ANA)已被发现具有降低血压,引发心动过缓,舒张血管,抑制中枢和外周神经系统释放神经递质及抗心律失常等效应。本实验在正常离体大鼠心脏模型上观察了anandamide及其受体拮抗剂对心功能的影响,以探讨anandamide的心脏效应及机制;并采用联苯胺荧光分光光度法观察了anandamide对心肌NO水平和NOS活性的影响。目的研究内源性大麻素类物质花生四烯乙醇胺(anandamide)对大鼠离体心脏的药理作用及机制并观察其对大鼠心肌一氧化氮(NO)含量和一氧化氮合酶(NOS)活性的影响。方法采用Langendorff方法观察anandamide对大鼠离体心脏心率(HR)、冠脉流量(CF)、冠脉灌注压(CPP)、左室压最大上升速率(+dp/dtmax)、左室压最大下降速率(-dp/dtmax)、左室收缩峰压(LVSP)、左室舒张末压(LVEDP)及左室发展压(LVDP)的影响;一氧化氮(NO)含量和一氧化氮合酶(NOS)活性采用联苯胺荧光分光光度法测定。结果Anandamide可使离体心脏心率(HR)、冠脉灌注压(CPP)、左室压最大上升速率(+dp/dtmax)、左室压最大下降速率(-dp/dtmax)、左室收缩峰压(LVSP)、左室发展压(LVDP)降低,使左室舒张末压(LVEDP)升高,冠脉流量(CF)增加。选择性大麻素CB1受体拮抗剂AM251(1μmol·L-1)阻断anandamide的部分心脏效应;另一选择性大麻素CB2受体拮抗剂AM630(1μmol·L-1)对anandamide的心脏效应无显著影响。NOS抑制剂L-N-硝基精氨酸甲酯(L-NAME)(100μmol·L-1)对anandamide的心脏效应也无显著影响。Anandamide能增强原生型NOS(cNOS)活性,抑制诱生型NOS(iNOS)活性,促进心肌NO的释放。结论Anandamide使离体大鼠心肌收缩力降低,心率减慢,表现出负性肌力和负性频率作用;Anandamide舒张冠脉,增加冠脉流量;大麻素CB2受体可能不参与anandamide的这些心脏效应,内源性NO也可能不参与调节anandamide的心脏效应;可能存在其他新的作用位点调节anandamide的心脏效应。Anandamide调节心肌NOS同工酶活性,增加cNOS活性,降低iNOS活性,促进NO的释放,可能发挥心肌保护作用,在心肌缺血和高血压治疗中有潜在应用前景。更多还原

【Abstract】 Marijuana(Cannabis sativa) is a kind of herbage, which was used to cure disease 1,000 years ago. Marijuana has many active ingredients. People have a new knowledge of the medical value of cannabinoids due to the studies on molecular level in the past twenty years. The endocannabinoid anandamide has been shown to elicit depressor effects, bradycardia, vasorelaxation, inhibition of neurotransmission and antiarrhythmic effect. To study its cardiac responses and mechanism, we observed the effects of anandamide and its receptor antagonists on heart function of isolated rat hearts under normal perfusion and on NO content and NOS activity in rat 1eft ventricular heart by benzidine-fluorescence spectrophotometry.ObjectiveTo observe the pharmacological effects of anandamide on the heart of rat in vitro and on NO content and NOS activity in rat 1eft ventricular heart.MethodsLangendorff method was used to observe the pharmacological effects of anandamide on heart rate(HR), coronary flow(CF), coronary perfusion pressure (CPP),maximal rate of left ventricular developed pressure(+dp/dtmax), maximal rate of left ventricular decline pressure(-dp/dtmax),left ventricular systolic pressure(LVSP),left ventricular end-diastolic pressure(LVEDP) and left ventricular developed pressure(LVDP) among rats experimented on. NO content and NOS activity were measured by benzidine-fluorescence spectrophotometry. ResultsAnandamide decreased HR, CPP, +dp/dtmax, -dp/dtmax, LVSP, and LVDP. Anandamide increased LVEDP and CF. The selective CB1 receptor antagonist AM251(1μmol·L-1) blocked part of cardiac responses to anandamide. Another selective CB2 receptor antagonist AM630(1μmol·L-1) and the nitric oxide synthase inhibitor N-omega- nitro-L-arginine methyl ester (L-NAME) (100μmol·L-1) had no significant effect on cardiac responses to anandamide. Anandamide could increase the cNOS activity , inhibit the iNOS activity and stimulate the release of NO from the myocardium.ConclusionsAnandamide decreased the contractility of heart muscle and slowed down the heart rate, showing negative inotropic action and negative chronotropic action. Anandamide caused coronary vasodilatation and coronary flow increase. Cannabinoid CB2 receptors and endogenous NO probably do not mediate those cardiac responses to anandamide. It is likely that other novel sites mediate cardiac responses to anandamide. By regulating myocardial NOS isoenzyme activity, increasing the cNOS activity ,inhibiting the iNOS activity and stimulating the release of NO, anandamide may be play a role of myocardial protection and have a potential application prospect in therapy of myocardial ischemia and hypertension.更多还原