Evaluation of Vasorlaxant Effect of Achillea Wilhelmsii Hydroalcholic Extract on Isolated Aorta in Rat

Achillea is well known herb in traditional medicine which has anticonvulsant and tonic effects, however; it is used to treat tachycardia and angina pectoris. Some reports of antihypertensive and hypotensive effects of Achillea wilhelmsii are published. This study aimed to investigate the vasorelaxant effect of Achillea wilhelmsii hydroalcholic extract on isolated aorta in rat. It was an interventional study in which 42 male Wistar rats (weighed 200-250 g) were divided randomly into 6 groups. In groups 1 and 2 the effect of the extract (1, 5 and 25 mg/ml) on contracted aorta by phenylephrine in intact and denuded endothelium were investigated. In groups 3 and 4 the effect of the extract on contracted aorta by chloride potassium in intact and denuded endothelium were investigated. In groups 5 and 6 the effect of the extract (5 mg/ml) on contracted aorta by phenylephrine and chloride potassium in the presence of cumulative calcium concentrations were evaluated by isolated tissue setup. In intact aorta contracted by phenylephrine, the extract relaxed 8%, 47% (p<0.001) and 45% (p<0.001), respectively, at concentrations 1, 5 and 25 mg/ml. In denuded endothelium aorta contracted by phenylephrine the extract relaxed 16% (p<0.05), 56% (p<0.001) and 54% (p<0.001), respectively, at concentrations 1, 5 and 25 mg/ml. In intact aorta contracted by chloride potassium the extract relaxed 18% (p<0.01), 57% (p<0.001) and 57% (p<0.001), respectively, at concentrations 1, 5 and 25 mg/ml. In denuded endothelium aorta contracted by chloride potassium the extract relaxed 2.5%, 47% (p<0.001) and 54.5% (p<0.001), respectively, at concentrations 1, 5 and 25 mg/ml. The extract (5 mg/ml) relaxed 7% (p<0.001), 12% (p<0.001), 22% (p<0.001) and 31.5% (p<0.001). The extract (5 mg/ml) relaxed 5.5% (p<0.01), 9.3% (p<0.001), 19% (p<0.001) and 74% (p<0.001) the contracted aorta by chloride potassium in the presence of cumulative calcium concentrations (from 10-5 to 10-2 respectively). The extract showed endothelium-independent vasorelaxant effect. The relaxation mainly was mediated by inhibition of voltage- and receptor-dependent Ca2+ channels in vascular smooth muscle cells.