Invited Symposium: Medicinal Plants and Drug Actions
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.
Back to the top.
| Discussion Board | Next Page | Your Symposium |
|Takemura, H.; (1998). Effects of Tetrandrine on Calcium Mobilization in Non-excitable Cells. Presented at INABIS '98 - 5th Internet World Congress on Biomedical Sciences at McMaster University, Canada, Dec 7-16th. Invited Symposium. Available at URL http://www.mcmaster.ca/inabis98/kwan/takemura0224/index.html|
|© 1998 Author(s) Hold Copyright|