Effect of ROS inhibition on lethal toxin-induced autophagy. A-D: Isolated cardiomyocytes were incubated with LeTx (100 ng/ml) for 3 h in the absence or presence of the NAC (500 μM). A: Representative gel blots depicting expression of Beclin-1, Atg-7, LC-3 and GAPDH (used as loading control); B: Beclin-1; C: Atg-7; D: LC3-II. Each lane in a treatment group on the gel represents sample from independent experiment. Mean ± SEM, n = 4 independent isolations per group, *P <0.05 vs. control group, # P <0.05 vs. LeTx group. Effect of autophagy induction or inhibition on lethal toxin induced cardiac contractile dysfunction. E-J: Isolated cardiomyocytes from WT and CAT mice were incubated with lethal toxin (100 ng/ml) for 3 h in presence or absence of the autophagy inhibitor 3-methyladenine (3-MA, 10 mM) or autophagy inducer rapamycin (5 μM) respectively. E: Peak shortening (PS, normalized to resting cell length); F: Maximum velocity of shortening (+ dL/dt); G: Maximum velocity of relengthening (- dL/dt); H: time-to-90% re-lengthening (TR90). Mean ± SEM, n = 60 to 75 cells from three mice per group, *P <0.05 vs. WT group, # P <0.05 vs. WT-LeTx group.