Fig. 4. Effect of rotenone treatment on MRC5 fibroblasts. (A) Cell viability in cells treated with different rotenone concentrations for 4 hours. (B) Rotenone titration curve of mitochondrial complex-I activity (), cellular endogenous respiration (), and cell proliferation (), expressed as percent of untreated control. (C) Inhibition of cell respiration and proliferation in galactose medium, expressed as percent of untreated control. Notice the threshold effect. (D) Morphological changes of the mt-network in cells treated with increasing rotenone concentrations. i, 0 ng/ml; ii, 3 ng/ml; iii, 6 ng/ml. Results are given as the mean ± s.d., n=3; ^*P<0.05, statistically significant change compared with the not induced.