Objective:To investigate the effects of epoxyaurapten on the function of smooth muscle myosin and the contractility of isolated intestinal smooth muscle strips.Method: Mg2+-ATPase activity and phosphorylation of myosin and contractility of isolated intestinal smooth muscle strips were chosen to determine the effects of epoxyaurapten on the activity of smooth muscle myosin and smooth muscle contractility.Result: Epoxyaurapten（40-320 μmol·L-1） exerted inhibitory effects on myosin Mg2+-ATPase activity in the presence of Ca2+/calmodulin and in a dose-dependent manner;and epoxyaurapten（40-320 μmol·L-1） exerted inhibitory effects on myosin phosphorylation in the presence of Ca2+/calmodulin and in a dose-dependent manner.Epoxyaurapten inhibited the muscle contraction of isolated rat intestinal strips in a dose-dependent manner

antagonized the stimulation induced by neostigmine and acetylcholine.Synergy inhibition on contractile activity was induced by concurrent use of atropine.Conclusion: Epoxyaurapten has prominent inhibition on the contractile activity of isolated rat intestine strips

which may be related to inhibition of the function of smooth muscle myosin.