Endoplasmic Reticulum Stress Inhibition Alleviates Tourniquet-Induced Limb Ischemia-Reperfusion Injury

Tourniquet-induced limb ischemia-reperfusion (I/R) injury can cause significant skeletal muscle damage, yet the role of endoplasmic reticulum (ER) stress in this context remains poorly understood. In this study, a mouse model of hindlimb I/R injury was established by applying an orthodontic rubber band for 4 h, followed by 24 h of reperfusion. To investigate the involvement of ER stress and the therapeutic potential of sodium 4-phenylbutyric acid (4-PBA), a clinically available ER stress inhibitor, mice were pretreated with 4-PBA (40 or 100 mg/kg, intraperitoneally) before ischemia. ER stress activation and associated pathological responses were assessed using qRT-PCR, Western blot analysis, immunohistochemistry, histological staining, and transmission electron microscopy. Our results demonstrated that I/R induced pronounced ER stress activation in gastrocnemius muscle, which was closely associated with enhanced oxidative stress, inflammation, and apoptosis. Pretreatment with 4-PBA effectively attenuated ER stress and disrupted these detrimental feedback loops, thereby reducing tissue damage, preserving histological integrity, and improving microcirculation perfusion. Collectively, these findings underscore ER stress as a central mediator of limb I/R injury and support ER stress inhibition as a promising therapeutic strategy for attenuating skeletal muscle damage in tourniquet-associated clinical settings.