Westerfield M, Joyner R W
Neuroscience. 1982 Jun;7(6):1367-75. doi: 10.1016/0306-4522(82)90250-0.
The roles of rectification and cable properties of the squid giant axon in determining the shape of synaptic potentials generated at the giant synapse were investigated. Excitatory postsynaptic potentials were recorded in response to selective stimulation of the main presynaptic axon at various temperatures. Excitatory postsynaptic potentials elicited at low temperatures (less than 18 degrees C) exhibited a marked after-hyperpolarization or undershoot, while those recorded at higher temperatures did not. The postsynaptic current, recorded under voltage clamp conditions, did not show an undershoot. Furthermore, intracellular injection of tetraethylammonium chloride, to block the voltage-dependent rise in potassium conductance, also eliminated the undershoot of the excitatory postsynaptic potential. These results indicate that the duration of synaptic potentials at the squid giant synapse is reduced by rectification due to a delayed rise in potassium conductance. Computer simulations of these synaptic potentials suggested that the effects of rectification will be more prominent in spherical (isopotential) cells than in cells with more complicated geometries.
研究了鱿鱼巨大轴突的整流作用和电缆特性在决定巨大突触处产生的突触电位形状方面的作用。在不同温度下，通过选择性刺激主要突触前轴突记录兴奋性突触后电位。在低温（低于18摄氏度）下诱发的兴奋性突触后电位表现出明显的后超极化或负后电位，而在较高温度下记录的则没有。在电压钳制条件下记录的突触后电流没有显示出负后电位。此外，细胞内注射氯化四乙铵以阻断钾电导的电压依赖性升高，也消除了兴奋性突触后电位的负后电位。这些结果表明，由于钾电导的延迟升高，整流作用缩短了鱿鱼巨大突触处突触电位的持续时间。对这些突触电位的计算机模拟表明，整流作用在球形（等电位）细胞中比在几何形状更复杂的细胞中更为显著。
