Wittmann I, Puppi A, Dely M
Central Laboratory of Animal Research, University Medical School, Pécs, Hungary.
Chem Biol Interact. 1987;63(2):115-25. doi: 10.1016/0009-2797(87)90092-5.
In isolated frog heart it was established that methylene-blue (MB, an oxidizing agent) decreased, while ascorbate (ASC, a reducing agent) increased the frequency of autorhythmic heart contractions. After MB treatment, in parallel with this phenomenon, the extracellular K+ concentration [K+]o showed a slow increase, but following ASC application a slow decrease occurred. Since these correlations are in good accordance with the idea that the pacemaking ability of heart, among other properties, depends on the voltage and time-dependent decrease in potassium conductance following the spike, changes in [K+]o might be one mechanism by which oxidizing and reducing agents modulate heart frequencies. On the basis of the effect of insulin (INS) and K-strophantoside (STR) on these modulatory influences, it is presumed that the changes in slow delta [K+]o transients might result, at least partly, from the effect of redox agents on the active transport system. In light of the increase in passive K+ fluxes after oxidant treatment and the decrease in this parameter following reductant treatment an effect of redox agents on the characteristics of the K+-channel is also postulated.
在离体蛙心实验中发现，亚甲蓝（MB，一种氧化剂）会降低自律性心脏收缩的频率，而抗坏血酸盐（ASC，一种还原剂）则会增加这种频率。在用MB处理后，与此现象同时出现的是，细胞外钾离子浓度[K⁺]ₒ缓慢升高，但在应用ASC后则出现缓慢下降。由于这些相关性与以下观点高度一致，即心脏的起搏能力，除其他特性外，取决于动作电位后钾离子电导随电压和时间的依赖性降低，[K⁺]ₒ的变化可能是氧化和还原剂调节心脏频率的一种机制。基于胰岛素（INS）和毒毛花苷K（STR）对这些调节作用的影响，推测缓慢的δ[K⁺]ₒ瞬变的变化可能至少部分是由于氧化还原试剂对主动转运系统的作用。鉴于氧化剂处理后被动钾离子通量增加以及还原剂处理后该参数降低，还假定氧化还原试剂对钾离子通道特性有影响。
