Imanishi Takashi, Matsushima Kayoko, Kawaguchi Akinori, Asano Hajime, Funakami Yoshinori, Wada Tetsuyuki, Masuko Takashi, Yoshida Shigeru, Ichida Seiji
Department of Pharmacy, Laboratory of Biological Chemistry, School of Pharmacy, Kinki University, Higashiosaka, Japan.
Neurochem Res. 2009 May;34(5):1011-9. doi: 10.1007/s11064-008-9839-x. Epub 2008 Dec 12.
Characteristics for the up-regulated response in the concentration of intracellular calcium ion (Ca(2+)) and in the sodium ion (Na(+)) current by serotonin (5-HT) were investigated in differentiated neuroblastoma x glioma hybrid NG108-15 (NG) cells. The results for the changes in Ca(2+) by 5-HT were as follows, (1) The 5-HT-induced Ca(2+) response was inhibited by 3 x 10(-9) M tropisetron (a 5-HT(3) receptor blocker), but not by other types of 5-HT receptor blockers; (2) The 5-HT-induced Ca(2+) response was mainly inhibited by calciseptine (a L-type Ca(2+) blocker), but not by other types of Ca(2+) channel blockers or 10(-7) M TTX (a voltage-sensitive Na(+) channel blocker); (3) When the extracellular Na(+) was removed by exchange with choline chloride or N-methyl-D-glucamine, the 5-HT-induced Ca(2+) response was extremely inhibited. The results for the 5-HT-induced Na(+) current by the whole cell patch-clamp technique were as follows, (1) The 5-HT-induced Na(+) current in differentiated cells was significantly larger than that in undifferentiated cells; (2) The ED(50) value for 5-HT-induced Na(+) current in undifferentiated and differentiated cells was almost the same, about 4 x 10(-6) M each other; (3) The 5-HT-induced Na(+) current was completely blocked by 3 x 10(-9) M tropisetron, but not by other 5-HT receptor antagonists and 10(-7) M TTX. These results suggested that 5-HT-induced Ca(2+) response in differentiated NG cells was mainly due to L-type voltage-gated Ca(2+) channels allowing extracellular Na(+) to enter via 5-HT(3) receptors, but not through voltage-gated Na(+) channels.
在分化的神经母细胞瘤x胶质瘤杂交NG108-15（NG）细胞中，研究了血清素（5-羟色胺，5-HT）引起的细胞内钙离子浓度（Ca(2+)）上调反应和钠离子（Na(+)）电流的特征。5-HT引起的Ca(2+)变化结果如下：（1）5-HT诱导的Ca(2+)反应被3×10(-9)M托烷司琼（一种5-HT(3)受体阻滞剂）抑制，但不被其他类型的5-HT受体阻滞剂抑制；（2）5-HT诱导的Ca(2+)反应主要被钙信号抑制剂（一种L型Ca(2+)阻滞剂）抑制，但不被其他类型的Ca(2+)通道阻滞剂或10(-7)M河豚毒素（一种电压敏感性Na(+)通道阻滞剂）抑制；（3）当用氯化胆碱或N-甲基-D-葡糖胺交换去除细胞外Na(+)时，5-HT诱导的Ca(2+)反应受到极大抑制。全细胞膜片钳技术检测5-HT诱导的Na(+)电流结果如下：（1）分化细胞中5-HT诱导的Na(+)电流明显大于未分化细胞中的；（2）未分化和分化细胞中5-HT诱导的Na(+)电流的半数有效剂量（ED(50)）值几乎相同，彼此约为4×10(-6)M；（3）5-HT诱导的Na(+)电流被3×10(-9)M托烷司琼完全阻断，但不被其他5-HT受体拮抗剂和10(-7)M河豚毒素阻断。这些结果表明，分化的NG细胞中5-HT诱导的Ca(2+)反应主要是由于L型电压门控Ca(2+)通道允许细胞外Na(+)通过5-HT(3)受体进入，而不是通过电压门控Na(+)通道。
