Pharmacological effects of berberine on the longitudinal muscle of the guinea-pig isolated ileum.
Pharmacological effects of berberine on the longitudinal muscle of the guinea-pig isolated ileum.
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发表时间：
1991-03
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通讯作者：
C. Tsai;R. Ochillo
中科院分区：
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作者：
C. Tsai;R. Ochillo
本文观察了小檗碱对豚鼠离体回肠纵肌收缩的影响。较低浓度的小檗碱（小于或等于5 × 10（-5）M）诱导乙酰胆碱的剂量-反应曲线平行移动，表明小檗碱竞争性拮抗乙酰胆碱对受体的作用。在较高浓度下，小檗碱（1 × 10 ~（-4）M）使乙酰胆碱的剂量-反应曲线发生明显的位移，最大反应降低，表明两种药物的相互作用由竞争性拮抗变为非竞争性拮抗。竞争性拮抗作用是由于乙酰胆碱在毒蕈碱受体上的作用，而非竞争性拮抗作用可能是由于小檗碱在除毒蕈碱受体位点外的其他位点上的作用。小檗碱剂量依赖性拮抗毒蕈碱，一种特异性的毒蕈碱受体激动剂的作用，以类似于乙酰胆碱的拮抗作用的方式，提供了小檗碱的作用部位是在毒蕈碱受体的证据。Hexamethonium（7.5 × 10 ~（-4）M）不影响小檗碱对乙酰胆碱浓度-反应曲线的作用，小檗碱对组胺引起的收缩也无影响，提示小檗碱对M受体具有特异性。小檗碱还浓度依赖性地减少电诱导的胆碱能收缩，其作用与毒蕈碱受体位点相对应。小檗碱对作用于感受器后部位的KCl引起的收缩没有影响。小檗碱的作用是可逆的，并取决于与制剂孵育的时间;与组织孵育的时间越长，恢复越慢。这一系列实验的结果支持了小檗碱阻断毒蕈碱受体的假设，这可能是其在减少肠道运动和治疗腹泻中的功效的部分解释。
The effects of berberine on the contractions of the longitudinal muscle of the guinea-pig isolated ileum were investigated. Lower concentrations of berberine (less than or equal to 5 x 10(-5) M) induced a parallel rightward shift of the dose-response curve of acetylcholine, suggesting that berberine is antagonizing the actions of acetylcholine at the receptors competitively. At higher concentration, berberine (1 x 10(-4) M) facilitated a rightward shift of the dose-response curve of acetylcholine with a reduction of maximum response, indicating that the interactions of the two agents changed from competitive to noncompetitive antagonism. The competitive antagonism is due to the actions of acetylcholine at the muscarinic receptors, while the noncompetitive antagonism is probably due to the action of berberine at other sites in addition to the muscarinic receptor sites. Berberine dose-dependently antagonized the effects of muscarine, a specific muscarinic receptor agonist, in a fashion similar to the antagonism of acetylcholine, providing evidence that the site of action of berberine is at the muscarinic receptors. Hexamethonium (7.5 x 10(-4) M) did not influence the effect of berberine on the concentration-response curve of acetylcholine and berberine had no effects on the contractions of the preparation elicited by histamine, suggesting its specificity for muscarinic receptors. Berberine also concentration-dependently reduced electrically induced cholinergic contractions, corresponding with its effects at the muscarinic receptor sites. Berberine had no effects on the contractions elicited by KCl, which acts at postreceptor sites. The action of berberine was reversible and dependent on the duration of incubation with the preparation; the longer the time of incubation with the tissues, the slower the recovery. The results of this series of experiments support the hypothesis that berberine blocks muscarinic receptors and this might be part of the explanation of its efficacy in the reduction of intestinal motility and in the treatment of diarrhea.