Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
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Tetrandrine (TET) is known to have inhibitory effects on Ca2+ mobilization in non-excitable cells as well as excitable cells. Because the mechanism of the action of TET on Ca2+ mobilization in non-excitable cells is unknown, the effects of TET on Ca2+ mobilization were examined in non-excitable rat glioma C6 cells. TET alone did not affect the resting cytoplasmic Ca2+ concentration ([Ca2+]i). TET inhibited the peak and sustained elevation of [Ca2+]i induced by bombesin, an inositol 1,4,5-trisphosphate (IP3)-generating agent, and thapsigargin (TG), a microsomal Ca2+ ATPase inhibitor, in a dose-dependent manner. TET inhibited IP3 accumulation elevated by bombesin. In permeabilized C6 cells, pretreatment with TET abolished Ca2+ release from intracellular stores induced by bombesin and TG. In the absence of extracellular Ca2+, the addition of Ca2+ to extracellular medium slightly increased [Ca2+]i, which indicates Ca2+ entry due to leakage of Ca2+ at the plasma membrane. TET did not affect this leakage entry of Ca2+. The present results suggest that TET inhibits Ca2+ release from intracellular stores as well as Ca2+ entry from extracellular medium evoked by bombesin and TG, and that TET inhibits IP3 accumulation induced by bombesin in non-excitable rat glioma C6 cells.

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Presentation Number SAtakemura0224
Keywords: Tetrandrine, Glioma C6 cells, Calcium, Bombesin, Thapsigargin