[Mechanism of action of ginsenoside Rb1 in decreasing intracellular Ca2+]

Using fluorescent probe Fura-2/AM, ginsenoside Rb1 (10, 50 and 100 mumol.L-1) was shown to dose-dependently reduce intracellular Ca2+ concentration of freshly dissociated brain cells isolated from newborn rats. It was also found to increase the fluidity of synaptosome membrane impaired by FeSO4-Cystein. Rb1 (10 mumol.L-1) shifted the dose-response curve to the right and decreased the maximal response in isolated mouse tail artery. Rb1 (10 and 100 mumol.L-1) was also found to reduce 5-HT-induced contraction of isolated rat basilar artery. With the whole-cell patch clamp technique, Rb1 (100 mumol.L-1) was shown to have no obvious effect on calcium current and potassium current. However, Rb1 was shown to increase Na(+)-K+ ATPase and Ca(2+)-Mg2+ ATPase activities at low dose in rat cerebral cortical synaptosomes. The results indicate that decrease of [Ca2+]i by Rb1 may be attributed to increase of ATPase activity.