Fig. 7. Preconditioning delays mitochondrial permeability transition pore (mPTP) opening in human embryonic stem cell-derived cardiomyocytes. (A ) mPTP opening was induced by photoexcitation-generated oxidative stress and detected by rapid dissipation of tetramethylrhodamine ethyl ester (TMRE) fluorescence. (B ) Representative signal traces from control (Ctrl), cyclosporine A (CsA)-treated cells, and anesthetic-induced preconditioning (APC). Arbitrary mPTP opening time was determined as the time when TMRE fluorescence intensity decreased by half between initial and residual fluorescence intensity. (C ) mPTP blocker CsA and APC increased arbitrary mPTP opening time, which was blocked in presence of 5-hydroxydecanoate (APC + 5-HD). Preconditioning with 40 μM H2O2(H2O2-PC) also delayed mPTP opening. *P < 0.05 versus Ctrl; # P < 0.05 versus APC + 5-HD.