Fig. (2).

Representative graphs of DFF fluorescence visualizing intracellular ROS levels of NTera-2 (NT2) deruived LHON cybrids, carrying either the ND4 mutation at np11778 or normal mtDNA, over a period of ten minutes, using confocal real-timeimaging. After 100 seconds, H₂O₂ (100 µM) was added in order to saturate antioxidant defence mechanisms of the cybrids.

It can be seen that Vit C (100 µM vitamin C) completely abolished the enhanced ROS levels of LHON cybrids. The PTP inhibitor CsA (cyclosporine A, 3 µM) was used in this set of experiments, since CsA had been found to partially inhibit calcium deregulation and cell death following stimulation of the LHON cybrids with an inhibitor of the smoth endoplasmic reticulum ATPase (thapsigargin). Since CsA did not influence DFF fluorescence, the measured ROS levels were not associated with permeability transition, which may occur after H₂O₂ addition. Modified according to [30].