During
tourniquet application, blood flow is restricted to a limb to stop excessive limb
hemorrhage in a
trauma setting and to create a bloodless operating field in the surgical setting. During
tourniquet-related
ischemia, aerobic respiration stops, and
ATP is depleted, and during subsequent reperfusion, there is an increase in
reactive oxygen species (ROS) production and other endogenous substances, which leads to acute
ischemia-reperfusion (IR)
injuries, including tissue
necrosis and skeletal muscle contractile dysfunction. Hyperbaric
oxygen (HBO)
therapy can increase the arterial
oxygen tension in the tissues of patients with general
hypoxia/
anoxia, including
carbon monoxide poisoning, circulatory arrest, and cerebral and
myocardial ischemia. Here, we studied the protective effects of HBO pretreatment with 100%
oxygen at 2.5 ATA against
tourniquet/IR injury in mice. After one hour of HBO
therapy with 100%
oxygen at 2.5 ATA was administered to C57/BL6 mice, a rubber band was placed at the hip joint of the unilateral hindlimb to induce 3 h of
ischemia and then released for 48 h of reperfusion. We analyzed gastrocnemius muscle morphology and contractile function and measured the levels of
ATP and ROS accumulation in the muscles. HBO pretreatment did not improve
tourniquet/IR-injured gastrocnemius muscle morphology and muscle contraction.
Tourniquet/IR mice with HBO pretreatment showed no increase in
ATP levels in IR tissues, but they did have a decreased amount of ROS accumulation in the muscles, compared to IR mice with no HBO pretreatment. These data suggest that one hour of HBO pretreatment with 100%
oxygen at 2.5 ATA increases the
antioxidant response to lower ROS accumulation but does not increase
ATP levels in IR muscles and improve
tourniquet/IR-injured muscle morphology and contractile function.