Abstract
Berberine $(10^{-7}-10^5M)$ increased the contractility dose-dependently in isolated rabbit ileal and jejunal segments. Atropine and hemicholinium abolished this response but not mecamylamine. Berberine$(10^{-8}-10^5M)$ enhanced the transmurally-stimulated(80 V, 0.5 ms, 0.05 Hz) twitch response in the isolated guinea-pig ileal segments. Atropine and hemicholinium also abolished this response but not mecamylamine. Effect of KCI, carbachol and histamine were not affected by pretreatment with berberine$(10^{-5}M)$. The results of our study suggest that berberine increases the intestinal contractility by increasing a small amount of acetylcholine release from the postganglionic parasympathetic nerve terminal but not by a direct activation of muscarinic receptors.