Witte O W, Speckmann E J, Walden J
Electroencephalogr Clin Neurophysiol. 1987 Jan;66(1):43-55. doi: 10.1016/0013-4694(87)90137-4.
Focal epileptiform activity was induced by local application of penicillin to the surface of the rat motor cortex. Neurons located within the epileptic focus displayed typical paroxysmal depolarization shifts (PDS). The participation of membrane calcium currents in the generation of PDS was examined by injecting the quaternized calcium entry blocker D890 into single neurons by iontophoresis or by pressure pulses. After intracellular injections of D890, PDS were depressed in amplitude by up to 55%. In a few cases the depression of PDS following intracellular application of D890 was preceded by a transient increase. Similar increases of PDS amplitude were obtained by injections of the calcium chelator EGTA. Control experiments in preparations without epileptic activity revealed that excitatory potentials elicited by thalamic stimulation and Cl(-)-dependent inhibitory postsynaptic potentials evoked by epicortical stimulation were not affected by intracellular D890. In these experiments successful intracellular drug application was verified by monitoring the transient shift of the Cl(-)-equilibrium potential induced by injection of KCl together with D890. It is concluded that in the penicillin-induced epileptic focus of the motor cortex Ca2+ inward currents participate in the generation of neuronal PDS.
通过将青霉素局部应用于大鼠运动皮层表面来诱发局灶性癫痫样活动。位于癫痫病灶内的神经元表现出典型的阵发性去极化偏移（PDS）。通过离子电渗法或压力脉冲将季铵化钙通道阻滞剂D890注入单个神经元，研究膜钙电流在PDS产生中的作用。细胞内注射D890后，PDS的幅度降低高达55%。在少数情况下，细胞内应用D890后PDS的降低之前会有短暂的增加。通过注射钙螯合剂EGTA也获得了类似的PDS幅度增加。在没有癫痫活动的标本中进行的对照实验表明，丘脑刺激引起的兴奋性电位和皮层刺激诱发的Cl(-)依赖性抑制性突触后电位不受细胞内D890的影响。在这些实验中，通过监测注射KCl和D890引起的Cl(-)平衡电位的短暂变化来验证细胞内药物应用是否成功。得出的结论是，在青霉素诱发的运动皮层癫痫病灶中，Ca2+内向电流参与了神经元PDS的产生。
