BACKGROUND:Previous studies have demonstrated that intracellular Ca~(2+)([Ca~(2+)]_i) overload, excitotoxicity,free radical injury,and nitric oxide toxicity are involved in mechanisms of neuronal death in the ischemic brain. OBJECTIVE:To investigate the influence of Panax quinquefolium saponins(PQS) on multiple factors-induced Ca~(2+) overload in the rat pheochromocytoma(PC12) cell line. DESIGN,TIME AND SETTING:Intergroup comparison,in vitro study.The experiment was performed at the Heilongjiang Key Laboratory of Anti-fibrosis Biotherapy,Mudanjiang Medical University between November 2007 and April 2008. MATERIALS:In vitro cultured PC12 cells in the logarithmic phase were assigned into blank control,model,and drug treatment groups(10μmol/L nimodipine;40μg/L,100μg/L,and 250μg/L PQS).Nimodipine was purchased from Jiangsu Yangtze River Pharmacy Group Co., China;PQS(purity>95%,HLPC grade) was provided by School of Basic Medical Sciences,Jilin University.Caffeine,Na_2S_2O_4,L-glutamic acid(Glu),Fura-2/AM,and calcium ionophore A23187 were purchased from Sigma,USA. METHODS:PC12 cells in the model and drug treatment groups were separately incubated in glucose-free Hank’s buffered saline solution + Na_2S_20_4(2 mmol/L) for 6 hours,Glu(200μmol/L) plus A23187(0.05μmol/L) for 6 hours,KCI(50 mmol/L) for 1 hour,and caffeine(5 mmol/L) for 3 hours to establish models of intracellular Ca~(2+) overload induced by oxygen and glucose deprivation,Glu,A23187,high K~+,or caffeine.In addition,control cells were incubated in high-glucose DMEM culture medium. MAIN OUTCOME MEASURES:[Ca~(2+)]_i changes in PC12 cells exposed to oxygen-glucose deprivation,Glu,A23187,high K~+,or caffeine were detected using spectrofluorometer. RESULTS:PQS blocked the[Ca~(2+)]_i increase induced by oxygen-glucose deprivation,Glu, A23187,high K~+,or caffeine.In particular,high-dose PQS was most effective(P<0.01).PQS significantly inhibited Glu- or caffeine-induced[Ca~(2+)]_i increases in the absence of extracellular Ca~(2+),but nimodipine did not. CONCLUSION:PQS blocked intracellular Ca~(2+) overload induced by oxygen-glucose deprivation, Glu,A23187,high K~+,or caffeine.This mechanism might be involved in the attenuation of neuronal apoptosis following ischemic brain injury. BACKGROUND:Previous studies have demonstrated that intracellular Ca~(2+)([Ca~(2+)]_i) overload, excitotoxicity, free radical injury, and nitric oxide toxicity are involved in mechanisms of neuronal death in the ischemic brain. OBJECTIVE :To investigate the influence of Panax quinquefolium saponins(PQS) on multiple factors-induced Ca~(2+) overload in the rat pheochromocytoma(PC12) cell line. DESIGN,TIME AND SETTING:Intergroup comparison,in vitro study.The experiment was Performed at the Heilongjiang Key Laboratory of Anti-fibrosis Biotherapy, Mudanjiang Medical University between November 2007 and April 2008. MATERIALS: In vitro cultured PC12 cells in the logarithmic phase were assigned into blank control, model, and drug treatment groups (10 μmol/L nimodipine 40 μg/L, 100 μg/L, and 250 μg/L PQS). Nimodipine was purchased from Jiangsu Yangtze River Pharmacy Group Co., China; PQS (purity > 95%, HLPC grade) was provided by School of Basic Medical Sciences, Jilin University.Caffeine,Na_2S_2O_4,L-glutamic a Cid(Glu), Fura-2/AM, and calcium ionophore A23187 were purchased from Sigma, USA. METHODS: PC12 cells in the model and drug treatment groups were separate culture in glucose-free Hank’s buffered saline solution + Na_2S_20_4 (2 mmol/ L) for 6 hours, Glu (200 μmol/L) plus A23187 (0.05 μmol/L) for 6 hours, KCI (50 mmol/L) for 1 hour, and caffeine (5 mmol/L) for 3 hours to establish models of Intracellular Ca~(2+) overload induced by oxygen and glucose deprivation, Glu, A23187, high K~+, or caffeine.In addition, control cells were cultured in high-glucose DMEM culture medium. MAIN OUTCOME MEASURES: [Ca~( 2+)]_i changes in PC12 cells exposed to oxygen-glucose deprivation, Glu,A23187,high K~+,or caffeine were detected using spectrofluorometer. RESULTS:PQS blocked the[Ca~(2+)]_i induced induced by oxygen -glucose deprivation, Glu, A23187, high K~+, or caffeine.In particular, high-dose PQS was most effective (P<0.01). PQS significantly inhibited Glu- or caffeine-induced [Ca~(2+)]_i Increases in the absence of the extrac Ellular Ca~(2+), but nimodipine did not. CONCLUSION: PQS blocked intracellular Ca~(2+) overload induced by oxygen-glucose deprivation, Glu, A23187, high K~+, or caffeine.This mechanism might be involved in The attenuation of neuronal apoptosis following ischemic brain injury.