Kocsis J D, Rand M N, Chen B, Waxman S G, Pourcho R
Department of Neurology, Yale University School of Medicine, New Haven, CT 06510.
Brain Res. 1993 Jul 9;616(1-2):273-82. doi: 10.1016/0006-8993(93)90218-c.
Intracellular Ca2+ was imaged in cultured neonatal rat retinal neurons using the Ca(2+)-sensitive dye fluo-3 and confocal scanning laser microscopy. Depolarization via elevation of bath K+ concentration resulted in large cytoplasmic and nuclear Ca2+ signals; responses in the nucleus exceeded those of the cytoplasm. Glutamate or kainate application elicited the same intracellular pattern of elevated Ca2+ signals. Kainate stimulation was blocked by the non-NMDA receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), and greatly reduced by removing Ca2+ from the bath and adding ethylene glycol-bis (beta-amino-ethyl ether) N,N,N',N'-tetraacetic acid (EGTA). Kainate was equally effective in eliciting Ca2+ signals when bath Na+ was replaced with equimolar concentrations of choline, or in the presence of the NMDA receptor antagonist, 2-amino-5-phosphonovaleric acid (APV). Caffeine treatment significantly reduced the kainate-induced intracellular Ca2+ response. These results suggest that Ca2+ can enter through the kainate receptor of retinal neurons and amplify the Ca2+ signals in the cytoplasm and nucleus by releasing Ca2+ from intracellular stores.
利用钙敏感染料fluo-3和共聚焦扫描激光显微镜对培养的新生大鼠视网膜神经元中的细胞内钙离子进行成像。通过提高细胞外钾离子浓度进行去极化会导致大量细胞质和细胞核内的钙离子信号；细胞核中的反应超过细胞质中的反应。应用谷氨酸或海人酸会引发相同的细胞内钙离子信号升高模式。海人酸刺激被非NMDA受体拮抗剂6-氰基-7-硝基喹喔啉-2,3-二酮（CNQX）阻断，并且通过从细胞外液中去除钙离子并添加乙二醇双（β-氨基乙醚）N,N,N',N'-四乙酸（EGTA）而大大降低。当用等摩尔浓度的胆碱替代细胞外液中的钠离子，或在存在NMDA受体拮抗剂2-氨基-5-磷酸戊酸（APV）的情况下，海人酸在引发钙离子信号方面同样有效。咖啡因处理显著降低了海人酸诱导的细胞内钙离子反应。这些结果表明，钙离子可通过视网膜神经元的海人酸受体进入，并通过从细胞内储存库释放钙离子来放大细胞质和细胞核中的钙离子信号。
