Cholesterol concentration in the gallbladder bile of Npc1+/+ and Npc1−/− mice at varying times following a single treatment with either saline or 2HPBCD. Groups of Npc1+/+ and Npc1−/− mice, all in the age range of 49 to 53 days, either remained untreated, or received a single sc injection of either saline (−) or 2HPBCD (+). At 24, 48 and 120 h later, gallbladder bile was obtained from several mice in each group for the measurement of cholesterol concentration. Values represent the mean±1 SEM of measurements in 5 to 10 mice in each group. Different letters (a–c) denote statistically significant differences between values (P<0.05) as determined by two-way ANOVA, with genotype, treatment, and time after treatment as variables.