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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Simultaneous activation of NADPH oxidase-related proton and electron currents in human neutrophils
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Simultaneous activation of NADPH oxidase-related proton and electron currents in human neutrophils

机译：人嗜中性粒细胞同时激活NADPH氧化酶相关质子和电子流

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摘要

Generation of reactive oxygen species by the NADPH oxidase complex is an important bactericidal weapon of phagocytes. Phor- bol myristate acetate (PMA) is a potent agonist for this "respiratory burst" in human neutrophils. Although stoichiometric H~~+ efflux occurs during the respiratory burst, efforts to stimulate voltage- gated H~~+ channels by PMA in whole-cell patch-clamped phago- cytes have been unsuccessful. We have used a modification of the permeabilized-patch configuration that allows control of intracel- lular pH and preserves second-messenger pathways. Using this method. we show that PMA dramatically enhances and alters voltage-gated proton currents in human neutrophils. PMA pro- duced four alterations in H~+ current properties, each of which increases the H~+ current at any given voltage: (i) a 40-mV negative shift in the H~+ conductance-voltage (g_H-V) relationship: (ii) faster activation [smaller activation time constant (τ_act)] during depolar- izing pulses; (iii) slower deactivation [larger deactivation time constant (τ_tail)] on repolarization: and (Iv) a larger maximum H~+ conductance (g_H,max). Inward current that directly reflects electron transport by NADPH oxidase was also activated by PMA stimula- tion. The identity of this electron current was confirmed by its sensitivity to diphenylene iodinium, an inhibitor of NADPH oxi- dase. Diphenylene iodinium also reversed the slowing of τ_tail with a time course paralleling the inhibition of electron current. How- ever, the amplitudes of H~+ and electron Currents activated by PMA were not correlated. A complex interaction between NADPH oxi- dase and voltage-gated proton channels is indicated. The data suggest that PMA stimulation modulates preexisting H~+ channels rather than inducing a new H~+ channel.
机译：NADPH氧化酶复合物产生活性氧是吞噬细胞的重要杀菌武器。醋酸肉豆蔻酸乙酸酯（PMA）是人类嗜中性粒细胞中这种“呼吸爆发”的有效激动剂。尽管在呼吸爆发期间发生化学计量的H ~~ +流出，但是通过PMA刺激全细胞膜片钳位的吞噬细胞中的电压门控H ~~ +通道的努力仍未成功。我们对通透膜的配置进行了修改，可以控制细胞内的pH值并保留第二信使途径。使用这种方法。我们表明，PMA可以显着增强和改变人类嗜中性粒细胞的电压门控质子电流。 PMA在H〜+电流特性上产生了四种变化，每种变化都会在任何给定电压下增加H〜+电流：（i）H〜+电导-电压（g_H-V）关系的负位移为40-mV ：（ii）在去极化脉冲期间激活速度更快[激活时间常数（τ_act）较小]； （iii）在复极化时减慢的失活[较大的失活时间常数（τ_tail）]：和（Iv）更大的最大H +电导（g_H，max）。通过PMA刺激也可以激活直接反映NADPH氧化酶进行电子传输的内向电流。该电子电流的身份已通过其对NADPH氧化酶抑制剂二亚苯基碘的敏感性得以证实。联苯二碘还以与电子电流抑制平行的时间过程逆转了τ_tail的减慢。但是，PMA激活的H〜+振幅和电子电流并不相关。指出了NADPH氧化酶和电压门控质子通道之间的复杂相互作用。数据表明，PMA刺激可调节先前存在的H〜+通道，而不是诱导新的H〜+通道。

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