华蟾蜍毒素增强5-羟色胺及拟交感胺对离体豚鼠输精管的收缩作用

Cinobufagin-induced potentiation on the contractions of the guinea-pig vas deferens to 5-hydroxytryptamine and sympathomimetic amines

华蟾蜍毒素(CB)10μmol·L^(-1)可促进5-羟色胺和酪胺使豚鼠输精管的收缩作用增强约3～4倍,经利血平及酚妥拉明处理后,则此增强作用明显减弱.CB也能明显增强麻黄碱及多巴胺对输精管的作用、唯正常输精管对此浓度几无反应,但输精管去神经以后,给此浓度时可立即出现节律性收缩.结果提示CB对豚鼠输精管的作用,可能存在微弱的直接作用和促进去甲肾上腺素释放的间接作用.

The effects of cinobufagin(CB)10μmol·L-1 on the contractile responses of the guinea-pig vas deferens to 5-hydroxytryptamine(5-HT 80μmol·L-1),tyramine(Tyr,29μmol·L-1),ephedrine(Eph,0.1mmol·L-1)and dopamine(DA,20μmmol·L-1)were examined.Responses to 5-HT and Tyr were about 3-4 fold potentiation by CB.Furthermore,in preparations treated with phentolamine(10μmol·L-1)or reserpine(2.0 mg·kg-1·d-1,2 d)the potentiation by CB markedly decreased.CB with the same concentration significantly potentiated the responses to Eph and DA as well.CB(10μmol·L-1)produced no visible effect inthe normal preparation,while tissue removed from animals one week after surgical denervation was still sensitive to CB(10μmol·L-1).In these experiments,it is suggested that the contraction to CB consists of two phases,the direct and indirect action.In the former,the contraction to CB(10μmol·L-1)appears in the denervated preparation.In the latter,CB-potentiation might be due to the increased NA release.