盐酸小檗碱对毒蕈碱型受体的作用

EFFECT OF BERBERINE HYDROCHLORIDE ON MUSCARINIC RECEPTORS

目的：研究盐酸小檗碱对乙酰胆碱系统的影响。方法：采用离体血管环、离体支气管螺旋体及放射配基受体结合实验等方法。结果：较低浓度的盐酸小檗碱（Ｂｅｒ）对乙酰胆碱的舒张反应有浓度依赖性的增强作用；而较高浓度的Ｂｅｒ可浓度依赖性地直接舒张带内皮的动脉环，此作用在去内皮或阻断Ｍ受体后被完全抑制。在豚鼠离体气管条上，Ｂｅｒ可引起浓度依赖性的收缩反应，而阿托品可阻断这种作用。放射配基受体结合实验显示盐酸小檗碱可特异性与大鼠脑组织的毒蕈碱受体结合，Ｋｉ值为１６μｍｏｌ·Ｌ－１。结论：盐酸小檗碱可激动毒蕈碱受体，从而引起血管的内皮依赖性的舒张反应及支气管的收缩。

AIM: To study the effect of berberine hydrochloride(Ber) on muscarinic receptors. METHODS: Use isolated arotic rings, isolated helical trachea strips and radioligandreceptor binding experiment. RESULTS: The inhibitory action of acetylcholine(ACh) on the contractile response of KCl in the endotheliumintact thoracic arotic rings of rats was potentiated by Ber concentrationdependently. At concentrations above 20 molL-1, Ber relaxed the endotheliumintact rings directly. The EC50 value was 315 molL-1. But such inhibitory action of Ber was totally abolished by removing the endothelium or by pretreatment with atropine 10 molL-1. Ber dosedependently induced contraction on isolated helical strips of guinea pig trachea. This action was completely blocked by atropine 10 molL-1. In the radioligandreceptor binding experiments, Ber was shown to bind to muscarinic receptors with definite affinity in rat brain. The Ki value was 16 molL-1. CONCLUSION: Ber is an agonist of muscarinic receptor. It may release EDRF from vascular endothelia cells by exciting muscarinic receptors to relax arotic rings.