环氧橙皮油素对平滑肌肌球蛋白功能及肠平滑肌收缩性的影响

目的:探讨环氧橙皮油素对平滑肌肌球蛋白功能及肠平滑肌收缩性的影响.方法:在纯化的蛋白体系中进行平滑肌肌球蛋白Ca2+依赖性磷酸化反应,采用甘油聚丙烯酰胺凝胶电泳测定肌球蛋白轻链磷酸化程度,孔雀绿法测定肌球蛋白Mg2+-ATPase活性.以平滑肌肌球蛋白Mg2+-ATPase活性、肌球蛋白磷酸化以及在克氏液中孵育的肠平滑肌收缩振幅为指标,考察环氧橙皮油素对平滑肌肌球蛋白Mg2+-ATPase活性和肌球蛋白磷酸化程度的调节作用,以及环氧橙皮油素对大鼠离体小肠平滑肌收缩性的影响.结果:在肌球蛋白轻链的Ca2+依赖性磷酸化反应中,在40～320 μmol·L-1浓度内环氧橙皮油素能抑制磷酸化肌球蛋白Mg2+-ATPase活性及其轻链磷酸化程度(P＜0.01),这种抑制作用与1-(5-氯-1-萘-磺酰)-六氢-1,4-二氮杂卓(ML-9)具有协同作用；40 - 320μmol·L-1浓度内环氧橙皮油素可剂量依赖性抑制大鼠离体小肠平滑肌收缩,且可拮抗新斯的明、乙酰胆碱引起的促进收缩作用,相加阿托品引起的抑制收缩作用(P＜0.01).结论:环氧橙皮油素可通过抑制平滑肌肌球蛋白的功能,抑制胃肠平滑肌的收缩性.

Effect of Epoxyaurapten on the Function of Myosin and the Contractility of Intestinal Smooth Muscle

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.