CA++ CHANNEL BLOCKING ACTIVITY OF ARTEMISIA-SCOPARIA EXTRACT

Intravenous administration of a hydro-methanolic extract of Artemisia scoparia (3-30 mg/kg) produced hypotensive and bradycardiac effects. These effects remained unaltered in atropine treated animals and the presence of the extract did not modify the vasoconstrictor response of norepinephrine, indicating that cardiovascular effects of the plant extract are not mediated through activation of muscarinic receptors or adrenoceptor blockade. In the in vitro studies, it suppressed the spontaneous movements of rabbit jejunum in a concentration-dependent (0.1-1 mg/mL) manner. The plant extract inhibited K+-induced tonic contraction in a manner similar to that of verapamil. Exposure of tissue to Ca++-free Kreb's solution abolished the spontaneous movements which were restored on addition of Ca++. In tissue pretreated with plant extract or verapamil, addition of Ca++ (50 mu M) failed to restore spontaneous contractions. These data indicate that Artemisia scoparia cntains Ca++ channel blocker-like constituent(s) which may explain the hypotensive effect observed in vivo and the traditional use of the plant as a spasmolytic.