Musabayane Cephas T, Kamadyaapa Dave R, Gondwe Mavuto, Moodley Kogi, Ojewole John A O
Department of Human Physiology, School of Medical Sciences, University of KwaZulu-Natal, Durban.
Cardiovasc J Afr. 2008 Sep-Oct;19(5):246-53.
The aim of this study was to examine some in vivo and in vitro cardiovascular effects of Helichrysum ceres leaf ethanolic extract (HCE) in experimental animal paradigms. The acute effects of HCE on blood pressure were studied in anaesthetised normotensive male Wistar rats challenged with intravenous hypotonic saline infusion after a 3.5-hour equilibration for four hours of one-hour control, 1.5-hour treatment and 1.5-hour recovery periods. HCE was added to the infusate during the treatment period. Sub-chronic hypotensive effects of HCE were examined in weanling Dahl saltsensitive (DSS) genetically hypertensive rats, which progressively develop hypertension with age, treated with HCE (80 mg/kg) every third consecutive day for seven weeks. Isolated atrial muscle strips, portal veins and descending thoracic aortic rings of healthy normotensive Wistar rats were used to investigate the vascular effects of HCE. Acute HCE administration caused a significant (p < 0.05) fall in blood pressure in the normotensive anaesthetised Wistar rats. DSS hypertensive rats treated with HCE displayed low arterial blood pressure and heart rate values from weeks five to seven. HCE produced concentrationdependent negative inotropic and chronotropic effects on rat isolated electrically driven left, and spontaneously beating right atrial muscle preparations, respectively. HCE also evoked concentration-dependent relaxation responses of endothelium-intact aortic rings and portal veins isolated from healthy normotensive Wistar rats. The vasorelaxant effects of HCE in intact aortic rings were significantly reduced, but not completely abolished by adding endothelial- derived factor (EDRF) inhibitor, L-NAME, suggesting that the vasorelaxant effect of the extract is mediated via EDRF-dependent and independent mechanisms. The results of the study suggest that the hypotensive action of HCE is elicited, in part, directly by decreasing myocardial contractile performance and total peripheral vascular resistance due to its negative inotropic and chronotropic effects on rat isolated atrial muscle strips; and vasorelaxant effects on isolated vascular smooth muscles. The observed cardiovascular effects of HCE partly support the basis for its use in the management of high blood pressure in folkloric medicine.
本研究的目的是在实验动物模型中考察蜡菊叶乙醇提取物（HCE）的一些体内和体外心血管效应。在麻醉的正常血压雄性Wistar大鼠中研究了HCE对血压的急性效应，在经过4小时平衡（1小时对照、1.5小时处理和1.5小时恢复）后，通过静脉输注低渗盐水进行挑战。在处理期间将HCE添加到输注液中。在断奶的Dahl盐敏感（DSS）遗传性高血压大鼠中检查了HCE的亚慢性降压作用，这些大鼠随着年龄增长逐渐发展为高血压，连续三天每天用HCE（80mg/kg）处理，共七周。使用健康正常血压Wistar大鼠的离体心房肌条、门静脉和胸主动脉降段环来研究HCE的血管效应。急性给予HCE导致正常血压麻醉Wistar大鼠的血压显著（p<0.05）下降。用HCE处理的DSS高血压大鼠在第5至7周显示出低动脉血压和心率值。HCE分别对大鼠离体电驱动的左心房肌和自发搏动的右心房肌制备物产生浓度依赖性的负性肌力和变时性效应。HCE还引起从健康正常血压Wistar大鼠分离的内皮完整的主动脉环和门静脉的浓度依赖性舒张反应。添加内皮衍生因子（EDRF）抑制剂L-NAME后，HCE在完整主动脉环中的血管舒张作用显著降低，但未完全消除，这表明提取物的血管舒张作用是通过EDRF依赖性和非依赖性机制介导的。研究结果表明，HCE的降压作用部分是通过对大鼠离体心房肌条的负性肌力和变时性效应以及对离体血管平滑肌的血管舒张作用，直接降低心肌收缩性能和总外周血管阻力而引起的。观察到的HCE的心血管效应部分支持了其在民间医学中用于治疗高血压的依据。
