RESUMO
The study aimed to elucidate the mechanism (s) of action of Ipomoea carnea leaf juice (ILJ) in changing contractility of guinea pig ileum. ILJ produced dose-dependent (10-10000 microg/ml) triphasic responses. The initial contractile phase was blocked by atropine (1 microg/ml) but had additive effect with acetylcholine (2 ng/ml) or carbachol (2 ng/ml). Neostigmine (30 ng/ml) or lignocaine (50 microg/ml) failed to alter the response. In cold-induced denervated preparations, this phase was augmented. The relaxatory phase of ILJ was not modified by phenoxybenzamine (35 microg/ml) but was reduced by propranolol (1 microg/ml) and abolished by lignocaine (50 microg/ml). The final contractile phase of ILJ was not affected by atropine (1 microg/ml). These results suggest that the triphasic response of ILJ is possibly mediated through cholinergic, adrenergic and non-cholinergic mechanisms, respectively.
