HG-induced oxidative damage was attenuated by ERAs or inhibition of mTOR. The H9c2 cells were seeded in low glucose medium overnight. Next, cells were treated with either HG alone for 24 h or pretreated with ambrisentan/bosentan (1 µM) for 1 h, followed by treatment with endothelin ET-1 (20 nM) for 3 h, followed by HG treatment for another 24 h. Additionally, another group of cells was transfected with siRNAs against Raptor/Rictor (20 nM) for 24 h followed by ET-1 (20 nM) treatment for 3 h and by HG treatment for another 24 h. (A,C) The intracellular ROS generation was determined using 5 μM DCFH-DA. The fluorescent signal was detected with wavelengths λex/λem: 485/530 nm. (B,D) MitoSOX (5 µM) was used to measure the mitochondrial superoxide production and the fluorescent intensity was captured at wavelengths λex/λem: 510/580 nm. (E) The MMP was estimated using JC-1 reagent (2.5 µM) and the fluorescent signal was recorded at wavelengths λem/λem: 590/530 nm. N = 4; Mean ± S.E.M.; * p < 0.05; *** p < 0.001.