药根碱对离体豚鼠心房的作用

Effects of jatrorrhizine on isolated guinea pig atria

药根碱使豚鼠左房收缩力和+dF/dt依浓度地增加,-dF/dt/df下降,收缩及舒张时间延长,并提高肾上腺素诱发的左房自律性降低乳头状肌的自律性。延长左房功能性不应期,降低右房自搏频率.药根碱能明显增强心肌的正性阶梯现象,对双脉冲刺激及静息后增强效应无影响。实验表明,药根碱对心肌的作用与小檗碱相似。其正性肌力作用与外Ca^(2+)内流有关,而不涉及细胞内Ca^(2+)的释放。

Jatrorrhizine(Jat)showed negative chronotropic and positive inotropic effects concentration-dependently on the isolated guinea pig atria.Time to peak tension and relaxation time were increased.The increase in +dF/dt was considerably greater than that in-dF/dt.When-dF/dt data were normalized for increasing in developed force(-dF/dt/dF)thc relaxation process was decreased by Jat.Jat(50μmol/L)prolonged the functional refractory period of the left atrium but the excitability was not affected.It depressed the automaticity induced by adrenaline in the papillary muscles and increased the automaticity induced by adrenaline in the left atria.Jat(100μmol/L)enhanced the positive stair-case phenomenon of the left atria,but didn t affect the response to paired stimulation and post-rest potentiation at the stimulation of 0.03 Hz.Only when left atria paced at 2 Hz Jat shows an increase in developed force.The experimental results suggest that the effect of Jat upon atria is similar to that of bcrberine.The effect that Jat increases myocardial tension development may be relevant to the increase of Ca2+ influx across sarcolemma and unrelated to the intraccllular Ca2+release.