Furthermore, intense signals of 4-hydroxynonenal (4-HNE), a reliable biomarker of lipid peroxidation in liver diseases [29], were detected in the liver tissue sections of AF-treated Akr1a1−/− mice, whereas relatively weak signals were observed in the liver tissue of mice in the other groups (Fig. 3J). Here, AKR1A1 is linked to atrial fibrillation.