Hablitz J J, Heinemann U
Department of Neurology, Baylor College of Medicine, Houston, Texas 77030.
Brain Res. 1987 Dec 1;433(2):299-303. doi: 10.1016/0165-3806(87)90036-8.
Picrotoxin-induced epileptiform activity was examined in neocortical slices prepared from 8- to 15-day-old rats. This activity consisted of spontaneous bursts of 3-5 discharges that resembled interictal spikes and were interspersed with ictal-like paroxysms lasting 10-30 s. Measurements of extracellular potassium ([K+]o) and calcium ([Ca2+]o) were made during these spontaneous epileptiform events, using ion-sensitive electrodes. Individual interictal spikes were associated with [Ca2+]o decreases of 0.1-0.2 mM, whereas sustained ictal-like discharges were accompanied by decreases of 0.3-0.4 mM. Measurement of [K+]o showed that individual interictal spikes were associated with increases in [K+]o up to 12 mM, whereas increases to more than 20 mM accompanied long-lasting ictal-like discharges. Maximum increases in [K+]o were observed ca. 600 microns below the pial surface. [K+]o increases were followed by undershoots of the resting [K+]o level. The unusually high [K+]o levels associated with epileptiform discharges in the immature neocortex suggest that disturbances in [K+]o regulation may contribute to the generation of the picrotoxin-induced, spontaneous, prolonged ictal-like discharges observed in the 8- to 15-day age group.
在从8至15日龄大鼠制备的新皮质切片中检测了印防己毒素诱导的癫痫样活动。这种活动由3 - 5次放电的自发爆发组成，类似于发作间期棘波，并穿插着持续10 - 30秒的发作样阵发。在这些自发癫痫样事件期间，使用离子敏感电极测量细胞外钾（[K + ]o）和钙（[Ca2 + ]o）。单个发作间期棘波与[Ca2 + ]o降低0.1 - 0.2 mM相关，而持续的发作样放电伴随着降低0.3 - 0.4 mM。[K + ]o测量表明，单个发作间期棘波与[K + ]o增加至12 mM相关，而增加至超过20 mM伴随着持久的发作样放电。在软脑膜表面以下约600微米处观察到[K + ]o的最大增加。[K + ]o增加之后是静息[K + ]o水平的低于基线。与未成熟新皮质中癫痫样放电相关的异常高的[K + ]o水平表明，[K + ]o调节紊乱可能有助于产生在8至15日龄组中观察到的印防己毒素诱导的、自发的、延长的发作样放电。
