Effects of high energy intake on the ex vivo cardiac mechanical function of hearts from Zucker Diabetic Fatty (ZDL) rats and their lean littermate (ZL, panel C) as well as high-fat (HF) diet fed rats and control animals perfused at fixed pressure (panel A) and at fixed coronary flow (panel E). The corresponding aconitase to fumarase ratio which is inversely proportional to the mitochondrial oxidative stress is located on the same line for each situation (panels B, D and F). The number of experiments was 10 per group. *: significantly different vs. control or ZL.