FIGURE 2.

Effects of 7-dehydrocholesterol (7DHC), cholesterol and 6-ketocholestanol (6KC) on the magnitude of dipole potential. THP-1 (A) or JY cells (B) were treated with 7DHC, cholesterol or 6KC at various concentrations between 12.5 and 200 μM and labeled with di-8-ANEPPS, which was followed by determination of the dipole potential-sensitive excitation ratio (R_{exc, di–8–ANEPPS}) using spectrofluorometry. R_{exc, di–8–ANEPPS} values were calculated from fluorescence intensities integrated between excitation wavelengths 410–440 nm and 490–520 nm and the mean (± SD) values of five independent experiments were plotted as a function of the applied concentrations of 7DHC (yellow), cholesterol (orange) and 6KC (red). Representative excitation spectra display shifts induced by the various sterols compared to controls (black) (C). Alternatively, control THP-1 (D) or JY (E) cells and those treated with 7DHC, cholesterol or 6KC were labeled with F66 and the emitted fluorescence intensities of individual cells were measured in the wavelength ranges 470–490 nm and 564–606 nm and the mean intensity ratio (R_{em, F66}) was calculated from data of at least 20,000 living cells per sample. The average values of five independent measurements (± SD) were plotted as a function of the applied concentrations of 7DHC, cholesterol and 6KC. Representative histograms containing data of individual cells display the shifts in R_{em, F66} values in response to the different sterols compared to controls (F). Asterisks (*) indicate significant differences obtained at maximal treatment concentrations compared to control samples (p < 0.05, ANOVA followed by Tukey’s HSD test).