Light-induced fluctuations in membrane current of single toad rod outer segments
Light-induced fluctuations in membrane current of single toad rod outer segments
复制标题
单蟾蜍杆外节膜电流的光致波动
作者：
K. Yau;T. Lamb;D. Baylor
脊椎动物的光感受器对光照做出反应，钠离子的稳定电流减少，钠离子在黑暗中穿过外节膜向内流动；这导致细胞超极化1。受体的光响应可以通过测量细胞外电压梯度2或细胞内记录1来研究，但由于细胞外电导率高和细胞之间存在电耦合，这些方法只能提供许多光感受器的平均信息3-;6。这种平均化以及光感受器6、7中暗电压噪声的存在阻碍了对单个光异构化的电效应的观察。为了尝试记录这些基本事件并定位暗噪声的来源，我们开发了一种记录单杆外段膜电流的方法。该技术基于 Neher 和 Sakmann8 在肌肉纤维上使用的技术。
VERTEBRATE photoreceptors respond to illumination with a reduction in the steady current of Na ions which in darkness flows inwards across the outer segment membrane; this results in hyperpolarisation of the cells1. The light responses of the receptors can be studied by measuring extracellular voltage gradients2 or by intracellular recording1, but these methods can only provide information averaged over many photoreceptors owing respectively to high extracellular conductivity and to the presence of electrical coupling between cells3–;6. This averaging and the presence of dark voltage noise in photoreceptors6,7 have prevented observation of the electrical effects of individual photoisomerisations. To try to record these elementary events and to localise the source of the dark noise, we have developed a method for recording the membrane current of a single rod outer segment. The technique is based on that used by Neher and Sakmann8 on muscle fibres.