Figure 4.

Effects of H₂O₂ and Nar on the mitochondrial oxidative metabolism activity and CRC. (a) H9c2 cells were treated with H₂O₂ and DMSO or Nar, and the mitochondrial oxidative metabolism activity was examined. (b–e) The cells were suspended in CRC medium and permeabilized with digitonin. To these cells, 0.25 M Calcium Green-5N and 5 mM succinate were added. This addition was followed by a series of Ca²⁺ pulses (10 nmoles) at 3-minute intervals until onset of the permeability transition (plateau). The Relative Fluorescence Unit (RFU) was recorded by spectrophotometer technique. ^∗p < 0.05 versus DMSO-treated cells. (b) Representative traces of the H9c2 cell treatments with H₂O₂ and vehicle are shown in dashed black and gray, respectively. (c) The results from the H₂O₂-treated cells are shown as the CRC normalized to the CRC of control (CRC₀). The data shown are the means ± SEM of three independent experiments. ^∗p < 0.05 versus vehicle. (d) Representative traces of senescent H9c2 cells cotreated with DMSO (dashed black), Nar (dark gray), and Nar + Pax (light gray). (e) The results from senescent cells treated with Nar and Nar + Pax are shown as the CRC normalized to the CRC of control (CRC₀). The data shown are the means ± SEM of three independent experiments. ^∗∗p < 0.01 versus DMSO-treated cells.