Effects of (1R,9S)-β-Hydrastine on Intracellular Calcium Concentration in PC12 Cells

(IR,9S)-beta-Hydrastine (BHS) decreases the basal intracellular Ca2+ concentration ([Ca2+](i)) in PC12 cells.(5)) This study examined the effects of (IR,9S)-BHS on [Ca2+](i) in PC12 cells. (1R,9S)-BHS at 10-100 mu m in combination with a high extracellular K+ level (56 mM) inhibited the release of dopamine in a concentration-dependent manner with an IC50 value of 66.5 mu m. BHS at 100 mu m inhibited the sustained increase in [Ca2+](i) induced by a high K+ level (56 mm), and had an inhibitory effect on the 2 mu m nifedipine-induced blockage of the K+-stimulated sustained increase in [Ca2+](i). In addition, (1R,9S)7BHS at 100 mu m prevented the rapid and sustained increase in [Ca2+](i) elicited by 20 mm caffeine, but did not have an effect on the increase induced by 1 mu m-,i thapsigargin, in the presence of external Ca2+. These results suggest that the active sites of (1R,9S)-BHS are mainly L-type Ca2+ channels and caffeine-sensitive Ca2+-permeable channels in PC12 cells.