Pharmacological characteristics of Artemisia vulgaris L. in isolated porcine basilar artery.

Ethnopharmacological relevance In Vietnamese traditional herbalism, there are conflicting opinions about the effect of Artemisia vulgaris L. (AVL, English name: mugwort) on hypertension. Some ethnic doctors recommend the use of AVL for treatment of hypertension, whereas others advise against it. The purpose of this study was to clarify the pharmacological characteristics of AVL in isolated arteries to explain the conflicts surrounding the use of AVL for treatment of hypertension. Materials and methods We initially performed a functional study using an organ bath system to investigate the effect of AVL extract on isolated porcine basilar artery. We then measured the change in intracellular free Ca 2+ concentration elicited by AVL using cultured smooth muscle cells loaded with the Ca 2+ indicator fluo-4. Finally, using HPLC, we determined the active components in AVL. Results and discussion AVL induced vasoconstriction at resting tension, and endothelial removal enhanced this effect significantly. Pretreatment with PD123319 (an AT 2 receptor antagonist), Nω - nitro - L - arginine (a nitric oxide synthase inhibitor), or both, also enhanced this effect. AVL-induced contraction was competitively inhibited by methiothepin (a 5-HT 1 and 5-HT 2 receptor antagonist) in the presence of ketanserin (a 5-HT 2 receptor antagonist). Removal of extracellular calcium with nifedipine (an L-type Ca 2+ channel blocker) or ruthenium red (a ryanodine receptor blocker) significantly reduced AVL-induced contraction, whereas losartan (an AT 1 receptor antagonist) and diphenhydramine (a H 1 receptor antagonist) had no effect on this contraction. AVL increased the intracellular free Ca 2+ concentration in cultured cells, and this increment was inhibited by methiothepin. HPLC analysis revealed that the retention time of the first peak in the AVL profile was similar to that of the 5-HT standard, and that addition of 5-HT to the AVL sample enhanced this peak. On the other hand, AVL induced endothelium-independent relaxation under precontracted conditions with 60 mM KCl. Captopril (an angiotensin converting enzyme inhibitor), atenolol (a β 1 receptor antagonist) and cimetidine (a H 2 receptor antagonist) had no effect on this relaxation. In Ca 2+ -free 60 mM KCl-containing solution, pretreatment with AVL significantly inhibited CaCl 2 -induced contraction. Conclusion For the first time, the present study has demonstrated that AVL has two opposite effects, contraction and relaxation, on isolated artery, which may help to explain the conflicting indications for AVL in traditional herbalism. 5-HT is a significant factor affecting artery contraction in the presence of AVL. [ABSTRACT FROM AUTHOR]