Cardiovascular Effects of Vernonia amygdalina in Rats and the Implications for Treatment of Hypertension in Diabetes.

Cardiovascular effects of aqueous extract of Vernonia amygdalina was investigated in normotensive Sprague-Dawley rats weighing 200-250g. Intravenous (femoral vein) administration of the extract at doses of 5.0 and 10.0mg/kg caused a bi-phasic alteration of blood pressure: an initial transient rise in mean arterial pressure which later fell to a considerably lower level than the starting blood pressure. This pattern of response was most clearly noticeable with the dose of 10 mg/kg whereby the mean arterial pressure of 73.7+3.4 mmHg rose to 101.9+4.1 mmHg in the first phase (P<0.01) before it finally fell to 60.2±2.5 mmHg in the second and final phase. Although higher doses (50 and 100mg/kg) caused more significant reduction in mean arterial pressure than the lower doses, the initial temporary elevation in blood pressure was not observed. Cumulative addition of the plant extract to isolated rings of aorta precontracted with noradrenaline produced a dose-dependent relaxation of the aortic smooth muscle. Maximum relaxation of 31.3±3.1% was observed with extract concentration of 2.7 mg/ml. These findings suggest that V. amygdalina has antihypertensive effect, and this could be mediated through direct vaso-relaxant mechanism. The implication of these results for the treatment of hypertension associated with diabetes is discussed. (Researcher. 2010;2(1):76-79).(ISSN: 1553-9865)