['To study the effects of dibenzocyclooctadiene lignans isolated from Schisandra chinensis, such as wuweizisu C, gomisin N, gomisin A, and schisandrin, on the membrane potential in C6 glioma cells.', 'The membrane potential was estimated by measuring the fluorescence change in DiBAC-loaded glioma cells.', "Wuweizisu C decreased the membrane potential in a concentration-dependent manner. Gomisin N and gomisin A, however, showed differential modulation and no change was induced by schisandrin or dimethyl- 4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate, a synthetic drug derived from dibenzocyclooctadiene lignans. We found no involvement of G(i/o ) proteins, phospholipase C, and extracellular Na(+) on the wuweizisu C-induced decrease of the membrane potential. Wuweizisu C by itself did not change the intracellular Ca(2+)[Ca(2+)](i) concentration, but decreased the ATP-induced Ca(2+) increase in C6 glioma cells. The 4 lignans at all concentrations used in this study did not induce any effect on cell viability. Furthermore, we found a similar decrease of the membrane potential by wuweizisu C in PC12 neuronal cells."] Does wuweizisu C from Schisandra chinensis decrease membrane potential in C6 glioma cells?