Remote ischemic preconditioning improves ileal microvascular oxygenation during rodent hemorrhagic shock without improving variables of microcirculation and mitochondrial respiration

Hemorrhagic shock is characterized by decreased microvascular blood flow, leading to a critical depletion of tissue oxygenation, particularly within the gastrointestinal tract. The integrity of the intestinal barrier, however, plays a crucial role in maintaining systemic homeostasis. Remote ischemic preconditioning (RIPC), achieved through transient, repeated occlusion of blood flow to a limb, has been shown to exert beneficial effects on various tissues under hypoxic conditions. These effects are at least in part attributed to circulating humoral mediators with vasoactive properties. This study aimed to investigate the effect of RIPC - implemented via intermittent bilateral hind limb perfusion occlusion - on intestinal microvascular oxygenation, regional microcirculation, and mitochondrial function in a fixed-pressure model of hemorrhagic shock in rats with subsequent autologous blood transfusion. RIPC ameliorated the decrease of microvascular oxygenation in the ileum (shock: 34 ± 4% vs. shock + RIPC: 48 ± 4%), but not in the colon (shock: 51 ± 2% vs. shock + RIPC: 50 ± 4%). RIPC had neither an effect on regional microcirculation nor on mitochondrial respiration assessed ex vivo post hemorrhage and transfusion. These findings suggest that RIPC may improve intestinal tissue oxygenation in hemorrhagic shock independently of regional microcirculation and mitochondrial respiration and that this protective effect of RIPC might vary between different sections of the gastrointestinal tract. The mechanism by which RIPC improves ileal tissue oxygenation has to be clarified in future studies.