Verma-Ahuja S, Evans M S, Pencek T L
Department of Surgery, Southern Illinois University School of Medicine, Springfield 62794, USA.
Epilepsy Res. 1995 Oct;22(2):137-44. doi: 10.1016/0920-1211(95)00040-2.
The genetically epilepsy-prone rat (GEPR) has become an important model to study genetic predisposition to epilepsy involving not only the brainstem but also forebrain structures. Previous work in CA1 hippocampal cells showed a reduction in spike frequency adaptation and only subtle changes in slow afterhyperpolarization (AHP). As important differences exist in calcium dependent potentials in the CA1 and CA3 hippocampal cells, we compared the membrane properties of hippocampal CA3 cells in GEPRs and Sprague-Dawley (SD) rats. There was no significant difference in the resting membrane potential, input resistance, charging time constant or rheobase between GEPRs and SD rat neurons. The action potential amplitude and the width at half maximal amplitude did not differ. A marked reduction in spike frequency adaptation accompanied by a very significant reduction in AHP was seen in the GEPR rats. Since calcium dependent potassium conductance produces both spike frequency adaptation and AHP, our results suggest that this conductance is reduced in the GEPR CA3 neurons.
遗传性癫痫易感性大鼠（GEPR）已成为研究癫痫遗传易感性的重要模型，不仅涉及脑干，还包括前脑结构。先前对CA1海马细胞的研究表明，动作电位频率适应性降低，慢后超极化（AHP）仅有细微变化。由于CA1和CA3海马细胞中钙依赖性电位存在重要差异，我们比较了GEPR大鼠和Sprague-Dawley（SD）大鼠海马CA3细胞的膜特性。GEPR大鼠和SD大鼠神经元之间的静息膜电位、输入电阻、充电时间常数或基强度没有显著差异。动作电位幅度和半最大幅度宽度也没有差异。在GEPR大鼠中观察到动作电位频率适应性显著降低，同时AHP也非常显著地降低。由于钙依赖性钾电导产生动作电位频率适应性和AHP，我们的结果表明，GEPR CA3神经元中的这种电导降低。
