An H2O2–Aldehyde Dehydrogenase2–Malondialdehyde Axis Underlies Mitochondrial Viscosity Elevationin Hepatic Ischemia–Reperfusion Injury

Hepatic ischemia–reperfusion injury (HIRI) is accompanied by oxidative stress and mitochondrial microenvironmental disruption, but how they are dynamically coupled remains unclear. Herein, a mitochondria-targeted dual-parameter probe, P3, was designed for simultaneous detection of mitochondrial viscosity and H2O2 to reveal their interrelationship and synergistic roles in HIRI. Using P3, we visualized the coordinated elevation of mitochondrial viscosity and H2O2 in HIRI from HepG2 cells to mouse liver, finding that both signals emerged during ischemia and were further amplified upon reperfusion. More importantly, a mitochondrial H2O2–aldehyde dehydrogenase 2 (ALDH2)–malondialdehyde (MDA)–mitochondrial viscosity cascade signaling pathway was uncovered in HIRI, elucidating the intrinsic link between abnormal mitochondrial viscosity and H2O2. This research establishes a strategy for simultaneously visualizing oxidative stress and mitochondrial microenvironmental remodeling during HIRI, and provides mechanistic insight into pathological coupling.