MECHANISM OF ACTION OF GINSENOSIDE Rb1 IN DECREASING INTRACELLULAR Ca²⁺

Using fluorescent probe Fura -2/ AM, ginsenoside Rb₁(10,50 and 100μmol·L^-1)was shown to dose- dependently reduce intracellular Ca²⁺ concentration of freshlydissociated brain cells isolated from newbern rats. It was also found to increase the fluidity of synapto-some membrane impaired by FeSO₄-Cystein, Rb₁(10μmol·L^-1) shifted the dose-response curve tothe right and decreased the maximal response in isolated mouse tail artery.Rb₁(10 and 100umol·L^-1) was also found to reduce 5-HT-induced contraction of isolated rat basilar artery;Withthe whole-cell patch clamp technique,Rb₁(100 μmol·L^-1)was shown to have no obvious effect oncalcium current and potassium current.However,Rb₁ was shown to increase Na⁺-K⁺ ATPase andCa²⁺-Mg²⁺ ATPase activities at low dose in rat cerebral cortical synaptosomes.The results indicatethat decrease of(Ca²⁺)i by Rb₁ may be attributed to increase of ATPase activity.