Effect of AID‐TAT peptide on reduction of NAD+ to NADH in vitro. A, Representative traces of NADH autofluorescence recorded in a myocyte before and after 5 minutes of exposure to 40 μmol/L of H2O2 followed by 5 minutes of exposure to 10 U/mL of catalase and a myocyte before and after 5 minutes of exposure to 0 μmol/L of H2O2 followed by 5 minutes of exposure to 10 U/mL of catalase. Vertical arrows indicate when drugs were added. NADH fluorescence decreased after addition of 4 mmol/L of sodium cyanide (NaCN), consistent with depletion of NADH after collapse of Ψm. B, Mean±SEM of changes in NADH autofluorescence for all myocytes exposed to 40 μmol/L of H2O2, 10 U/mL of catalase, and 10 μmol/L of nisoldipine (Nisol) as indicated. C, Representative traces of NADH autofluorescence recorded in myocytes before and after 5 minutes of exposure to 40 μmol/L of H2O2 followed by 5 minutes of exposure to 10 U/mL of catalase in the presence of either 1 or 10 μmol/L of AID(S)‐TAT or AID‐TAT peptide as indicated. Vertical arrows indicate when drugs were added. NADH fluorescence decreased after addition of 4 mmol/L of NaCN, consistent with depletion of NADH after collapse of Ψm. D, Mean±SEM of changes in NADH autofluorescence for all myocytes exposed to 40 μmol/L of H2O2, 10 U/mL of catalase, and 1 or 10 μmol/L of AID(S)‐TAT or AID‐TAT peptide as indicated. Statistical significance was determined using the Kruskal‐Wallis test followed by Dunn's multiple comparison test. AID indicates alpha‐interacting domain; NAD+, nicotinamide adenine dinucleotide; NADH, reduced nicotinamide adenine dinucleotide; TAT, transactivator of transcription.