Effects of 4‐Oxo‐2‐nonenal on biochemical properties of bovine heart mitochondria

The effects of lipid peroxidation products 4‐Hydroxy‐2‐nonenal (4‐HNE) and 4‐oxo‐2‐nonenal (4‐ONE) were evaluated using bovine heart mitochondria. Oxygen consumption rate (OCR), ultrastructure, antioxidant activity, and membrane permeability were examined to compare their effects on isolated mitochondria from beef cardiac muscle. For the mitochondrial morphology, the final concentration of mitochondria and 4‐ONE or 4‐HNE in the reaction tube were 10 mg/ml and 1 mM, respectively. For the OCR experiment, mitochondria (2.5 mg/ml) were incubated with 0.20 mM ONE or in a Clark electrode chamber at 25°C. Mitochondrial membrane permeability was determined by incubating 0.5 mg/ml of mitochondrial protein with either 0.05 mM ONE or HNE or ethanol control at pH 5.6 and 7.4 at 25°C. Transmission electron microscopy (TEM) revealed that the size of 4‐ONE treated mitochondria at pH 7.4 increased (p < .05), as did permeability (p < .05), unlike ethanol controls. However, mitochondria incubated with 4‐ONE at pH 5.6 showed a decrease in volume (p < .05). Incubating mitochondria with 4‐ONE at pH 5.6 and pH increased oxygen consumption rate 7.4 caused less oxygen consumption than either 4‐HNE treatment or ethanol control. The hydrogen peroxide assay (H(2)O(2)), ferric reducing antioxidant properties (FRAP), and 2,2’‐azinobis (3‐ethylbenzthiazoline‐6‐sulfonic acid) (ABTS.(+)) assays revealed that 4‐ONE is a more potent inhibitor of the endogenous antioxidant system of mitochondria than 4‐HNE (p < .05).