Na+ action potentials in human photoreceptors
Na+ action potentials in human photoreceptors
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DOI：
10.1016/s0896-6273(01)00299-9
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发表时间：
2001-05-01
期刊：
影响因子：
16.2
通讯作者：
Miyachi, E
中科院分区：
文献类型：
--
作者：
Kawai, F;Horiguchi, M;Miyachi, E
哺乳动物的光感受器在光刺激下超极化，通常被认为是非尖峰神经元。我们在手术切除的人类视网膜上使用了全细胞膜片钳技术，以检测人类光感受器是否可以诱发动作电位。我们发现人视杆细胞感受器表达电压门控性Na+通道，并产生Na+动作电位，响应于膜电位为-60或-70 mV的去极化。在使电位远低于-50 mV的光响应终止时，人类视杆细胞中的Na+尖峰被激发。当强光关闭时，这有助于放大神经递质的释放，从而选择性地放大对光信号的关闭反应。
Mammalian photoreceptors are hyperpolarized by a light stimulus and are commonly thought to be nonspiking neurons. We used the whole-cell patch-clamp technique on surgically excised human retina to examine whether human photoreceptors can elicit action potentials. We discovered that human rod photoreceptors express voltage-gated Na+ channels, and generate Na+ action potentials, in response to membrane depolarization from membrane potentials of -60 or -70 mV. Na+ spikes in human rods were elicited at the termination of a light response that hyperpolarized the potential well below -50 mV. This served to amplify the release of a neurotransmitter when a bright light is turned off, and thus selectively amplify the off response to the light signal.