Effects of hyperbaric oxygen on glucose, lactate, glycerol and anti-oxidant enzymes in the skeletal muscle of rats during ischaemia and reperfusion

1. Hyperbaric (HBO2) and topical oxygen represent two accepted options to oxygenate tissues. The aim of the present study was to investigate the effect of HBO2 on energy metabolism and anti-oxidant enzymes in a rat model of ischaemia-reperfusion (IR) skeletal muscle injury. 2. In the first study, 16 rats were randomized to a HBO2-treated group (Group 1; n = 8) and an untreated group (Group 2; n = 8). Under general anaesthesia, right hind limb ischaemia was produced by application of a rubber-band tourniquet for 3 h. After 2 h ischaemia, Group 1 rats received HBO2 during the last hour of ischaemia. The HBO2 consisted of 100% oxygen delivered at 282.8 kPa absolute pressure. Group 2 rats were not treated. Following the ischaemic period, the tourniquet was released for 1 h. A microdialysis probe was used to sample lactate, glucose and glycerol concentrations in the muscle extracellular tissue every 15 min throughout each experiment. 3. In the second study, 24 rats were randomized into four groups (n = 6 each). The first two groups were subjected to the IR injury protocol outlined above and either treated (Group 1) or untreated (Group 2) with HBO2. Group 3 rats were anaesthetized, did not undergo IR injury, but underwent HBO2 treatment. Group 4 rats were anaesthetized but did not undergo either IR injury or HBO2 treatment. At end of each experiment, the biceps femoris muscle was removed and assayed for superoxide dismutase (SOD) and catalase (CAT) activity. Malondialdehyde (MDA) was measured to estimate the extent of membrane lipid peroxidation. 4. Three hours of skeletal muscle ischaemia resulted in a gradual decrease in the glucose concentration and a gradual increase in the lactate concentration within the extracellular fluid of the affected skeletal muscle tissue. Treatment with HBO2 had no effect on the glucose concentration; however, HBO2 significantly attenuated the ischaemia-induced increase in lactate and glycerol. In both groups, glucose concentration increased rapidly during reperfusion; glucose concentration returned to pre-ischaemic levels 15 min after reperfusion both with and without HBO2. 5. Catalase activity and MDA increased significantly after 1 h of reperfusion. The HBO2 attenuated the reperfusion-induced increase in CAT activity and MDA. 6. The results of the study suggest that HBO2 may have some beneficial effect by decreasing lactate and glycerol levels and modulating anti-oxidant enzyme activity in postischaemic skeletal muscle in our rat model of tourniquet-induced IR skeletal muscle injury.