Fig. 3. Mitochondrial membrane fluidity is increased in HeLa cells with decreased DRP1 levels. (A) Mitochondrial respiratory rate measured in the presence of ascorbate-TMPD in wild-type (WT), not-induced (NI) or induced (I) HeLa cells. (B) Isolated activity of complex IV measured by spectrophotometry in the same cells. (C) The total content in cytochrome c determined by recording difference absorbance spectra. (D) DPH anisotropy measured in isolated mitochondria by fluorometry. The data indicate an increase in organelle membrane fluidity when DRP1 was silenced by RNAi. Results are given as the mean ± s.d., n=3; ^*P<0.05, statistically significant change compared with the NI cells.