摘要
钩藤碱(Rhy)及异钩藤碱(Isorhy)呈剂量依赖性减慢右心房自发节律,且不被Atr阻断,二药非竞争性地拮抗Iso和组胺正性变时作用,其pD_2值分别为Iso 5.45和5.57,H 5.28和5.48,并能取消CaCl_2的正性变时效应,Rhy和Isorhy还剂量依赖性地抑制心房收缩力,在1μmol·L^(-1)普萘洛尔存在下,二药对苯肾上腺素正性变力作用的量效曲线是非竞争性拮抗,其pD_2值分别为43.6和4.43.Rhy和Isorhy 0、3mmol·L^(-1)能显著抑制左心房静息后增强效应和阶梯现象.结果提示,Rhy和Isorhy的负性变时和变力作用,似与二药抑制心肌细胞膜Ca^(2+)转运有关。
In the isolated guinea pig right atria rhynchophylline(Rhy)and isorhynchophyllinc(Isorhy)showed a negative chronotropic effect,which was not prevented by alropine(0.1nmol·L-1).Rhy and Isorhy(10μmol·L-1)shifted the concentration-response curve for positive chronotropic action of isoprenaline and histamine to the right in a nonparallel manner,and depressed their maximal responses with a pD2 value of 5.45 and 5.57 for isoprenaline,and 5.28 and 5.48 for histamine respectively.They could abolish the positive chronotropic effect of CaCl,(0.5,2.5mmol·L-1).Rhy and Isorhy also depressed the contractile force of atria in a concentration-dependent manner.In the rat left atria,Rhy and Isorhy(10μmol·L-1)could uncompetitively antagonize the positive inotropic effect of phenylephrine in the presence of propranolol(1 μmol·L-1)and the pD2 values were 4.36 and 4.43respectively.Furthermore,Rhy and Isorhy(0.3 mmol·L-1)could markedly inhibit the post-rest potentiation and the positive staircase phenomenon,and Isorhy(0.3 mmol·L-1)could even reverse the latter to a negative one,so did verapamil 30μmol·L-1 The results suggest that Rhy and Isorhy produce the negative chronotropic and inotropic effects which are most likely to be in no association with cardiac M,β1 and H2 receptors,but may be related to the inhibition of transmembrane flux of calcium.
出处
《中国药理学与毒理学杂志》
CAS
CSCD
北大核心
1993年第2期117-121,共5页
Chinese Journal of Pharmacology and Toxicology
关键词
构藤碱
异构藤碱
变时作用
心房
Rhynchophylline Isorhyn-chophylline Chronotropic effect Inotropiceffect Heart atrium
