海马脑片锥体细胞的膜电性质和突触反应

ELECTROPHYSIOLOGICAL PROPERTIES AND SYNAPTIC RESPONSES OF CAl PYRAMIDAL NEURONS IN RAT HIPPOCAMPAL SLICES

应用成年大鼠海马脑片锥体神经元细胞内记录技术,测得CA_1区锥体细胞的静息电位为-78±6mV(n=16),膜电阻69±18MΩ,时间常数5.7±2.1ms,由I-V曲线求得斜率电阻57±15MΩ(n=8)。I-F曲线表明锋电位发放频率随去极化电流增大而升高(n=4).刺激Schaffer侧支通路可透发潜伏期为5±2ms(n=7)的兴奋性突触后电位,其幅值呈等级性,为低钙高镁溶液取消,其迟后成分在无镁溶液中增大,提示兴奋性氨基酸可能为介导递质。

With the conventional intracellular recording, the electrophysiological properties and synaptic responses of CA1 pyramidal cells were observed in rat hippocampal slices. It was found that the resting potential, membrane resistance and time constant was -78±6mV(n=16), 69±18MΩ, and 5.7± 2.1ms, and the amplitude, threshold and overshoot of the direct action potential was 91±6mV, 16±8mV and 12±7mV, respectively. From the I-V curves, the average slope membrane resistance was calculated to be 57±15MΩ(=8).By the depolarizing current pulse, it was observed that the discharging frequency of cells was current intensity-dependently increased(n=5). Moreover, the graded depolarizing responses were elicited by the stimulation of area CA3 with the latency of 5±2ms, time to peak 4±1ms and time of half decay 7±3ms, which were nullified by low Ca/high Mg and potentiated by Mg-free solution respectively. It was concluded that the responses were excitatory postsynaptic potentials and possibly mediated by the excitatory amino acids.