维拉帕米对触发活性的影响

EFFECT OF VERAPAMIL ON TRIGGERED ACTIVITY

本文使用经典细胞电生理方法,观察维拉帕米对后除极电位和触发活性的影响。4mMBa^(2+)灌注后,心肌标本(n=11)膜电位由83.1±4.4mV降至62.1±3.5mV,动作电位幅值也由119.3±10.1mV降至74.0±6.9mV,表现异常自律性占27.3%(3/11),EAD和DAD触发活性分别占45.4%(5/11)、27.3%(3/11)。维拉帕米灌注(1mg/L)后异常自律性明显减慢,EAD、DAD及相关的触发活性随之消失。这提示,异常自律性和触发活性可能与钙内流有关,维拉帕米具抑制作用。

Using microelectrode technique, we observed the effect of verapamil on afterdepolarization and triggered activity. Following perfusion of 4 mmol/L Ba^(2+), the resting membrane potential of the ventricular muscle cells was decreased from 83.1±4.4 mV to 62.1±3.5 mV, the action potential amplitude was reduced from 119.3±10.1 mV to 74.0±6.9 mV. The incidences of spontaneous activity were as follows: abnormal automaticity and triggered activity induced by EAD, DAD were 27.3% (3/11), 45.4% (5/11) and 27.3% (3/ 11), respectively. During exposure to verapamil (1 mg/L), the rate of abnormal automaticity was abolished. The results indicate that the mechanisms of abnormal automaticity and triggered activity are probably related to the inward current carrried by Ca^(2+), so verapamil has depressing effect.