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首页> 外文期刊>The European Journal of Neuroscience >Distinctive patterns of alterations in proton efflux from goldfish retinal horizontal cells monitored with self-referencing H +-selective electrodes
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Distinctive patterns of alterations in proton efflux from goldfish retinal horizontal cells monitored with self-referencing H +-selective electrodes

机译：自参照H +选择性电极监测的金鱼视网膜水平细胞质子外排变化的独特模式

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摘要

The H + hypothesis of lateral feedback inhibition in the outer retina predicts that depolarizing agents should increase H + release from horizontal cells. To test this hypothesis, self-referencing H +-selective microelectrodes were used to measure extracellular H + fluxes from isolated goldfish horizontal cells. We found a more complex pattern of cellular responses than previously observed from horizontal cells of other species examined using this technique. One class of cells had an initial standing signal indicative of high extracellular H + adjacent to the cell membrane; challenge with glutamate, kainate or high extracellular potassium induced an extracellular alkalinization. This alkalinization was reduced by the calcium channel blockers nifedipine and cobalt. A second class of cells displayed spontaneous oscillations in extracellular H + that were abolished by cobalt, nifedipine and low extracellular calcium. A strong correlation between changes in intracellular calcium and extracellular proton flux was detected in experiments simultaneously monitoring intracellular calcium and extracellular H +. A third set of cells was characterized by a standing extracellular alkalinization which was turned into an acidic signal by cobalt. In this last set of cells, addition of glutamate or high extracellular potassium did not significantly alter the proton signal. Taken together, the response characteristics of all three sets of neurons are most parsimoniously explained by activation of a plasma membrane Ca 2+ ATPase pump, with an extracellular alkalinization resulting from exchange of intracellular calcium for extracellular H +. These findings argue strongly against the hypothesis that H + release from horizontal cells mediates lateral inhibition in the outer retina.
机译：视网膜外侧反馈抑制的H +假设预示着去极化剂应增加水平细胞的H +释放。为了检验该假设，使用自参考H +选择性微电极测量来自分离的金鱼水平细胞的细胞外H +通量。我们发现比以前使用该技术检查过的其他物种的水平细胞观察到的细胞反应模式更为复杂。一类细胞具有初始站立信号，表明细胞膜附近的细胞外H +较高。谷氨酸盐，海藻酸盐或高细胞外钾的挑战诱导了细胞外碱化。钙通道阻滞剂硝苯地平和钴可减少这种碱化。第二类细胞显示出细胞外H +的自发振荡，被钴，硝苯地平和低细胞外钙所消除。在同时监测细胞内钙和细胞外H +的实验中，检测到细胞内钙的变化与细胞外质子通量之间存在很强的相关性。第三组细胞的特征是静置的细胞外碱化作用，该作用被钴转化为酸性信号。在这最后一组细胞中，添加谷氨酸盐或高细胞外钾并没有显着改变质子信号。综上所述，所有三组神经元的响应特征都可以通过质膜Ca 2+ ATPase泵的激活来最简单地解释，其中由于细胞内钙交换为细胞外H +而导致细胞外碱化。这些发现强烈反对从水平细胞释放H +介导外视网膜侧向抑制的假说。

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