Inenaga K, Akamatsu N, Nagatomo T, Ueta Y, Yamashita H
Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
Neurosci Lett. 1992 Dec 7;147(2):189-92. doi: 10.1016/0304-3940(92)90592-u.
To determine the function of intracellular free Ca2+ which is important in generating the phasic firing pattern characteristic of vasopressin neurons in the supraoptic nucleus (SON), we injected the highly specific Ca(2+)-chelating agent ethyleneglycol-bis-(beta-aminoethyl ether) N,N-tetraacetic acid (EGTA) into SON cells in the rat hypothalamic slice preparation. Intracellular recordings from 29 SON neurons which showed phasic firing were analyzed. Of the 29 SON neurons, 21 were recorded with microelectrodes filled with 3 M potassium acetate and 20 of the 21 neurons retained the phasic pattern more than 1 h after penetration by the electrode. Only one neuron lost phasic firing and fired randomly. By contrast, in all 8 neurons which were recorded with microelectrodes filled with 100 mM EGTA/2 M potassium acetate, phasic firing disappeared 10-80 min after penetration of the recording electrode although the neurons still showed spontaneous activity. These neurons also lost the after hyperpolarization and plateau potentials which followed bursting discharges. Our results suggest that intracellular free Ca2+ may play an important role in generating phasic firing.
为了确定细胞内游离钙离子在产生视上核（SON）中血管加压素神经元特征性的相位性放电模式中所起的作用，我们将高特异性的钙螯合剂乙二醇双（β-氨基乙基醚）N,N-四乙酸（EGTA）注入大鼠下丘脑脑片制备中的视上核细胞。对29个呈现相位性放电的视上核神经元进行了细胞内记录分析。在这29个视上核神经元中，21个是用填充有3M醋酸钾的微电极记录的，在这21个神经元中，有20个在电极刺入后1小时以上仍保持相位性放电模式。只有一个神经元失去了相位性放电并随机放电。相比之下，在用填充有100mM EGTA/2M醋酸钾的微电极记录的所有8个神经元中，在记录电极刺入后10 - 80分钟，相位性放电消失，尽管这些神经元仍表现出自发活动。这些神经元也失去了爆发性放电后的超极化后电位和平台电位。我们的结果表明，细胞内游离钙离子可能在产生相位性放电中起重要作用。
