Effects of stimulation and diphenylhydantoin on the intracellular sodium activity in Purkinje fibres of sheep heart.
Effects of stimulation and diphenylhydantoin on the intracellular sodium activity in Purkinje fibres of sheep heart.
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刺激和二苯内酰脲对绵羊心脏浦肯野纤维细胞内钠活性的影响。
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发表时间：
1985
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通讯作者：
D. Ellis
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作者：
D. Ellis
使用离子敏感微电极研究了刺激频率对绵羊心脏浦肯野纤维细胞内Na+活性（aiNa）的影响。aiNa在3 Hz时增加约44%，在0.2 Hz时增加约6.5%。增加的大小在制剂之间变化很大，并且似乎与刺激前的aiNa初始水平无关。在刺激过程中，aiNa呈指数上升，并在约15 min内达到新的稳态水平。该上升的时间常数与刺激频率无关。刺激一段时间后aiNa的恢复似乎也是指数的，但时间常数取决于刺激期间aiNa升高的程度，较大升高后的时间常数较短。将刺激对aiNa的影响与使用高浓度心脏活性类固醇抑制Na+-K+泵进行比较。通过测量Na+-K+-泵抑制后aiNa的上升速率来评估二苯基乙内酰脲（DPH）对细胞膜Na+渗透性的影响。浓度为10（-4）M时，DPH使aiNa升高速率降低约37%。DPH产生的Na+渗透性的降低可能是在静止制剂中观察到的aiNa减少的原因。DPH也产生了大量的减少aiNa在刺激的准备工作。这些结果与其已知的抗肿瘤作用有关。
The effects of stimulus frequency on the intracellular Na+ activity (aiNa) of Purkinje fibres from sheep hearts have been investigated using ion‐sensitive micro‐electrodes. aiNa increased by approximately 44% at 3 Hz and approximately 6.5% at 0.2 Hz. The size of the increase was very variable between preparations and did not appear to be related to the initial level of aiNa before stimulation. During stimulation, the rise of aiNa was exponential and gave a new steady‐state level within about 15 min. The time constant of this rise was independent of the frequency of stimulation. The recovery of aiNa following a period of stimulation also appeared to be exponential but the time constant was dependent upon the extent to which aiNa had been raised during stimulation, with shorter time constants following larger rises. The effects of stimulation on aiNa were compared to inhibition of the Na+‐K+ pump using high concentrations of cardioactive steroids. The influence of diphenylhydantoin (DPH) on the Na+ permeability of the cell membrane was assessed by measuring the rate of rise of aiNa following Na+‐K+‐pump inhibition. DPH decreased the rate of rise of aiNa by approximately 37% at concentration of 10(‐4) M. The decrease of Na+ permeability produced by DPH is probably responsible for the observed reduction of aiNa in quiescent preparations. DPH also produced substantial decreases of aiNa in stimulated preparations. These results are discussed in relation to its known anti‐arrhythmic effects.