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Ryanodine(R)可逆转洋地黄引起狗的定性心律失常。作者用离体电刺激的豚鼠乳头肌及记录细胞电活动的方法研究该药的作用机理。(R)(2μM)在刺激频率为0.5Hz和1Hz时,不影响动作电位去极化的最大速率(V_(max)),略延长复极90%处的动作电位时程。0.5Hz时,V_(max)的复极后恢复不受该药的影响。4例用高钾去极化的心脏制备,该药可轻度增加其V_(max),但不影响慢反应的V_(max)复极后的恢复。用固定浓度的异丙基肾上腺素(1μM)或双氢哇巴因(100μM),然后再逐渐增加细胞外钙浓度,直至出现恒定的迟后收缩和瞬间去极化。用(R)后可在5分钟内取消这两种现象。瞬间去极化若达到阈值则可引起自发性搏动。这种心律失常也可被(R)取消。
Ryanodine (R) reversible digitalis caused dog’s qualitative arrhythmia. In this study, the mechanism of action of this drug was studied by using the electrical stimulation of guinea pig papillary muscles and recording the electrical activity of the cells in vitro. (R) (2μM) did not affect the maximum rate of depolarization (V max) of the action potentials at stimulation frequencies of 0.5 Hz and 1 Hz, slightly prolonging the action potential duration at 90% repolarization. At 0.5 Hz, the V_ (max) repolarization recovery is unaffected by the drug. Four of them were prepared with high potassium depolarized heart, which slightly increased its V max, but did not affect the recovery of slow response V max repolarization. With a fixed concentration of isoproterenol (1 μM) or dihydrotalbaine (100 μM), the extracellular calcium concentration was then gradually increased until a constant delayed contraction and transient depolarization occurred. With (R) in 5 minutes to cancel these two phenomena. Instantaneous depolarization can cause spontaneous beats if the threshold is reached. This arrhythmia can also be canceled by (R).