L-carnitine protects C2C12 cells against mitochondrial superoxide overproduction and cell death

Figure 5 Protection of menadione-induced C2C12 cell death by L-carnitine. C2C12 cells were either untreated (white histogram) or pretreated with 500 μmol/L of L-carnitine (dark histogram) and incubated for 24 h with desired concentration of menadione (from 0 to 12 μmol/L). Cell survival was evaluated by the analysis of membrane permeability to PI measured by flow cytometry. Each value represents the average percentage of viable cells remaining in the total population ± standard values. Black histograms indicate the proportion (%) of C2C12 that was not PI positive. White histograms indicate the proportion (%) of C2C12 pretreated with L-carnitine that was not PI positive. A star on top of two histograms indicates a significant difference between untreated and L-carnitine treated cells (P < 0.05).