Studies on retinal amacrine cells using slice-patch method

无长突细胞是一组重要的次级神经元，可表现出多种多样的光诱发反应。对无长突细胞的主要兴奋性输入被认为源自双极细胞，而无长突细胞本身被认为向神经节细胞提供主要抑制性输入。金鱼视网膜中无长突细胞的光诱发反应可分为三大类，其中又有一些亚类。如细胞间记录所确定的，金鱼视网膜的无长突细胞可以通过产生短暂的、持续的去极化或持续的超极化反应来对光刺激作出反应。产生这些光诱发反应的机制仍然没有完全理解。为了阐明一些可能影响无长突细胞不同反应的因素，我们进行了全细胞膜片钳研究的无长突细胞的金鱼视网膜切片制备。无长突细胞主要有三种形态亚型。在无长突细胞中发现四种类型的电压门控电流：持续外向钾电流（I_K）、瞬时外向钾电流（I_A）、持续内向钙电流（I_A）和瞬时内向钠电流（I_A）。<Ca><Na>此外，在大多数无长突细胞中记录到由氯离子通过GABA_A受体携带的自发电流事件。

The amacrine cells are an important group of secondary neurons which can exhibit a wide variety of light-evoked responses. The main excitatory inputs to the amacrine cells are believed to originate from the bipolar cells while the amacrine cell itself is thought to provide the main inhibitory inputs to the ganglion cells. The light-evoked responses of the amacrine cells in the goldfish retina have been classified into three main groups with some subdivisions within these three main groups. As determined by intercellular recordings, amacrine cells of the goldfish retina can respond to a light stimulus by yielding a transient, a sustained depolarizing, or a sustained hyperpolarizing response. The mechanisms by which these variety of light-evoked responses is generated is still not completely understood. To elucidate some of the factors which might affect the differing responses of amacrine cells, we undertook the whole-cell patch clamp study of the amacrine cells of the goldfish retina in a slice preparation. Three main morphological subtypes of amacrine cells were observed. Four types of voltage-gated currents were identified in the amacrine cell : a sustained outward potassium current, I_K, a transient outward potassium current, I_A, a sustained inward calcium current, I_<Ca>, and a transient inward sodium current, I_<Na>. In addition, spontaneous current events, carried by chloride ions through GABA_A receptors, were recorded in most of the amacrine cells.