青藤碱对异丙肾上腺素、氯化钙及组胺剂量—效应关系的影响

本实验用离体肌鼠左房肌标本观察了青藤碱对异丙肾上腺素,氯化钙及组胺的剂量—效应关系的影响,青藤碱可使离体豚鼠左房的异丙肾上腺素剂量—效应曲线非平行右移,并降低最大反应值,pD′_2值为3.56±0.12,不同于β—受体阻断剂心得安。对氯化钙剂量—效应曲线的影响与钙通道阻滞剂戊脉安相似,表现为曲线非平行右移,最大反应降低,PD′_2值分别为3.43±0.11,6.13±0.16。对组胺剂量—效应曲线的影响与H_2—受体阻断剂甲氰咪胍不同,青藤碱呈非竞争性拮抗,pD′_2值为3.57±0.13。提示青藤碱的负性肌力作用可能在于阻滞钙通道,而不是竞争性阻断β—受体和H_2—受体。

EFFECTS OF SINOMENINE ON ISOPRENALINE、CALCIUNNEDIATED AND HISTAMINE DOSERESPONES RELATIONSHIP IN ISOLATED GUINEA PIG ATRIUM

The effects of sinomenine on isoprenlaline, calcinum-mediated and histamine gdose-response relationships were investi ated in isolated guinea pig atriapreparations. Sinomenine shilted isoprenaline dose-response curve to the right nonparallelly with the reduced crest values. When the pD'_2 value was 3.56±0.12, it is different from β-receptor blocker propranolo. The effect of sinomenine on calciummediated dose-response eurve was qualitatively similar to the calcium channel blocker verapamil. Thee urve was shifted to the right and maximum was decreased. The pD'_2 values were 3.43±0.11, 6.13±0.16, respectively. The effect of sinomenine on histamine dose-response curve was also different from H_2-receptor blocker cimetidine and prodiced a noncompetitive antagonism. The pD'_2 vaiue was 3.57±0.13 These results suggested that the negative inotvopic effect of sinomenine did not result from the blocked β-receptor and H_2-receptor, but from antagnizing calcium channel.