Pyruvate-Enhanced Fluid Resuscitation for Hemorrhagic Shock and Hindlimb Ischemia

Traumatic blood loss often necessitates the use of resuscitative fluids to replenish blood volume and stabilize blood pressure. The use of tourniquets to achieve hemostasis imposes ischemia-reperfusion on wounded limbs after release. Resuscitation with the physiological antioxidant and natural intermediary metabolite pyruvate may abrogate reperfusion injury of muscle by scavenging oxyradicals and stabilizing cytoprotective proteins. This study was designed to determine the effects of pyruvate in the setting of hemorrhagic shock with resuscitation and hindlimb ischemia-reperfusion. All experiments were conducted on isoflurane-anesthetized male goats. A controlled hemorrhage was performed to lower mean arterial pressure (MAP) to c. 50 mmHg, then the right femoral artery and vein were occluded for 90 min. Lactate Ringer’s (LR) or pyruvate Ringer’s (PR) was infused intravenously (10 ml/min) for 90 min, from 30 min occlusion until 30 min after reperfusion. At 4 h reperfusion, the right gastrocnemius muscle and left ventricular myocardium were biopsied and flash-frozen for analyses of metabolites, enzymes, pro- and anti-apoptotic proteins and markers of oxidative and inflammatory stress. During the first phase of experimentation we hypothesized that controlled resuscitation with PR vs. LR more effectively stabilizes MAP and attenuates myocardial inflammation post-resuscitation. MAP (mmHg) was increased in PR (59 ± 4) vs. LR (47 ± 3) resuscitated goats (p During the second phase of experimentation, we hypothesized that PR resuscitation would protect ischemic hindlimb muscle in the setting of hemorrhagic shock and limb reperfusion. Lactate dehydrogenase and creatine kinase activities fell by 36 and 20%, respectively in LR-resuscitated vs. sham muscle (p We conclude that 1) Systemic hypotension and hindlimb ischemia-reperfusion with conventional LR treatment imposed pro-oxidative and pro-inflammatory stress both systemically and locally, thus preventing stabilization of MAP during recovery and initiating apoptotic mechanisms in the hindlimb musculature; 2) Pyruvate-fortified Ringer’s effectively stabilized hemodynamics and dampened systemic inflammation after hemorrhagic shock with resuscitation and hindlimb ischemia-reperfusion; 3) PR-fortified resuscitation blunted oxidative and inflammatory stress within the ischemic hindlimb and suppressed pro-apoptotic signaling. These investigations demonstrate the anti-oxidative and anti-inflammatory effects of pyruvate in a system exposed to hemorrhagic shock with fluid resuscitation, as well as identify the cytoprotection pyruvate affords tissue experiencing ischemia-reperfusion.