Muscarinic activity of aqueous leaves extract of Excoecaria grahamii Stapf 1913 on rabbit blood pressure and toad isolated perfused heart

Excoecaria grahamii, African shrub, is used in many West African countries traditional medicine against different diseases as powerful purgative and biopesticide. There is little work about pharmacological effects of this plant because of its high toxicity. The effects of the aqueous extract of the plant was investigated on rabbit blood pressure and toad isolated and perfused heart activity. E. grahamii extracts (EGE) injection exhibited a dose dependent blood pressure decrease like acetylcholine effect. This activity was inhibited by atropine, suggesting muscarinic effect. Same results (inhibition effects) were found on both electrical and mechanical actions of toad isolated and perfused heart. Previous results obtained with aqueous extracts on smooth intestine muscle exhibit a muscarinic effect (hypotensive principle) then alcoholic extracts showed hypertensive and cardiotonic effects on rabbit. Our results confirm existence of muscarinic activity on rabbit blood pressure and toad heart activity. Key words: Excoecaria grahamii, rabbit blood pressure, toad heart, electrocardiogram.