Effects of H/RO (with different hypoxia durations) on mitochondrial functions in NARP cybrids and 143B cells.
(A) After treating 143B cells with H/RO (H: 6, 12, and 18 h; RO: 2 h), no obvious cardiolipin depletion was noted during recording. Mitochondria remained thread-like. (B) Cardiolipin depletion was noted gradually in NARP cybrids receiving H/RO with durations of hypoxia for 12 and 18 h. Mitochondria became swollen and round. (C) In 143B cells, only transient mCa2+ accumulation was noted (D) Marked and persistent mCa2+ accumulation was noted in NARP cybrids exposed to H/RO with duration of hypoxia for 18 h. (E) Red/green overlay of two consecutive confocal images (Δt = 2min) of 80 nM nonyl acridine orange (NAO) fluorescence in NARP cybrids and 143B cells upon H/RO with different hypoxia durations. The percentage of nonmoving mitochondria (overlapping mitochondrial area, in yellow color) to total mitochondrial area increased from 45 ± 3.2% to 63 ± 1.4% in 143B cells and 48 ± 5.1% to 77 ± 2.3% in NARP cybrids after the exposure of cells to H/RO with duration of hypoxia for 18 h. P-value representing statistically significant differences between NARP cybrids and 143B cells is indicated (*). (A′-E′) Quantitative analyses of A-E. n=6.