Characteristics for Enhanced Response of Serotonin-Evoked Ion Dynamics in Differentiated NG108-15 Cells |
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Authors: | Takashi Imanishi Kayoko Matsushima Akinori Kawaguchi Hajime Asano Yoshinori Funakami Tetsuyuki Wada Takashi Masuko Shigeru Yoshida Seiji Ichida |
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Affiliation: | (1) Laboratory of Biological Chemistry, Department of Pharmacy, School of Pharmacy, Kinki University, Kowakae 3-4-1, Higashiosaka 577-8502, Japan;(2) Laboratory of Cell Biology, Department of Pharmaceutical Sciences, School of Pharmacy, Kinki University, Kowakae 3-4-1, Higashiosaka 577-8502, Japan;(3) Department of Life Science, School of Science and Engineering, Kinki University, Kowakae 3-4-1, Higashiosaka 577-8502, Japan |
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Abstract: | Characteristics for the up-regulated response in the concentration of intracellular calcium ion ([Ca2+] i ) and in the sodium ion (Na+) current by serotonin (5-HT) were investigated in differentiated neuroblastoma × glioma hybrid NG108-15 (NG) cells. The results for the changes in [Ca2+] i by 5-HT were as follows, (1) The 5-HT-induced Ca2+ response was inhibited by 3 × 10−9 M tropisetron (a 5-HT3 receptor blocker), but not by other types of 5-HT receptor blockers; (2) The 5-HT-induced Ca2+ response was mainly inhibited by calciseptine (a L-type Ca2+ blocker), but not by other types of Ca2+ 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 Ca2+ 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 ED50 value for 5-HT-induced Na+ current in undifferentiated and differentiated cells was almost the same, about 4 × 10−6 M each other; (3) The 5-HT-induced Na+ current was completely blocked by 3 × 10−9 M tropisetron, but not by other 5-HT receptor antagonists and 10−7 M TTX. These results suggested that 5-HT-induced Ca2+ response in differentiated NG cells was mainly due to L-type voltage-gated Ca2+ channels allowing extracellular Na+ to enter via 5-HT3 receptors, but not through voltage-gated Na+ channels. |
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Keywords: | Differentiation Intracellular calcium ion NG108-15 cells 5-HT3 receptor Up-regulation 5-HT-evoked response |
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