Influence of hypoxic preconditioning in-vivo to 30 minutes knee surgery specific tourniquet application

Purpose: To establish whether a bout of hypoxic preconditioning (HPC) or ischemic preconditioning (IPC) would elicit a reduction in total knee replacement (TKR) surgery specific tourniquet mediated oxidative stress (OS) in-vivo. Methods: In an independent group design, 18 healthy men were exposed to 40 min of either: whole-body HPC (14.3% O2), IPC (four bouts of 5 min ischemia and 5 min reperfusion) or rest (SHAM), 1 h prior to 30 min TKR specific limb ischemia and 2 h reperfusion. Systemic blood samples were taken at pre- and post-intervention, additionally blood and gastrocnemius samples were obtained at pre-, 15 min post- (15PoT) and 120 min post-tourniquet deflation. Systemic leukocytes and gastrocnemius tissue were analysed for the heat shock protein (Hsp72) and Heat shock protein 32 (Hsp32) gene transcript response (indicates severity of the cellular stress response), with the systemic plasma also assessed for OS markers (protein carbonyl and glutathione (reduced, oxidised, total, reduced/oxidised-ratio)). Results: A 1.93 and 1.97 fold reduction in gastrocnemius Hsp72 was noted in individuals exposed to HPC (p = 0.007) and IPC (p = 0.006) respectively, in comparison to SHAM at 15PoT. No significant differences were observed in gastrocnemius Hsp32, systemic Hsp72, Hsp32 or OS markers (p > 0.05) between groups. Conclusions: HPC and IPC provided cytoprotection to ischemic stressed gastrocnemius tissue as indicated by an attenuated cellular stress response to 30 min TKR specific limb ischemia.