Abstract
BackgroundPostconditioning is a novel reperfusion technique to reduce ischemia-reperfusion injuries. The aim of the study was to investigate this method in an animal model of lower limb revascularization for purpose of preventing postoperative renal failure.MethodsBilateral lower limb ischemia was induced in male Wistar rats for 3 hours by infrarenal aorta clamping under narcosis. Revascularization was allowed by declamping the aorta. Postconditioning (additional 10 sec reocclusion, 10 sec reperfusion in 6 cycles) was induced at the onset of revascularization. Myocyte injury and renal function changes were assessed 4, 24 and 72 hours postoperatively. Hemodynamic monitoring was performed by invasive arterial blood pressure registering and a kidney surface laser Doppler flowmeter.ResultsMuscle viability studies showed no significant improvement with the use of postconditioning in terms of ischemic rhabdomyolysis (4 h: ischemia-reperfusion (IR) group: 42.93 ± 19.20% vs. postconditioned (PostC) group: 43.27 ± 27.13%). At the same time, renal functional laboratory tests and kidney myoglobin immunohistochemistry demonstrated significantly less expressed kidney injury in postconditioned animals (renal failure index: 4 h: IR: 2.37 ± 1.43 mM vs. PostC: 0.92 ± 0.32 mM; 24 h: IR: 1.53 ± 0.45 mM vs. PostC: 0.77 ± 0.34 mM; 72 h: IR: 1.51 ± 0.36 mM vs. PostC: 0.43 ± 0.28 mM), while systemic hemodynamics and kidney microcirculation significantly improved (calculated reperfusion area: IR: 82.31 ± 12.23% vs. PostC: 99.01 ± 2.76%), and arterial blood gas analysis showed a lesser extent systemic acidic load after revascularization (a defined relative base excess parameter: 1st s: IR: 2.25 ± 1.14 vs. PostC: 1.80 ± 0.66; 2nd s: IR: 2.14 ± 1.44 vs. PostC: 2.44 ± 1.14, 3rd s: IR: 3.99 ± 3.09 vs. PostC: 2.07 ± 0.82; 4th s: IR: 3.28 ± 0.32 vs. PostC: 2.05 ± 0.56).ConclusionsThe results suggest a protective role for postconditioning in major vascular surgeries against renal complications through a possible alternative release of nephrotoxic agents and exerting a positive effect on hemodynamic stability.
Highlights
Postconditioning is a novel reperfusion technique to reduce ischemia-reperfusion injuries
This present study further investigates the effect of postconditioning on muscle injury and the evolving renal dysfunction as a serious postoperative complication in a rat model of open abdominal aortic surgery
Till the end of the first postoperative day, a regeneration seemed to be in process in the PostC group, while in the IR group viability remained on a similar level as it was 4 hours after reperfusion. 72 hours after revascularization, a further improvement could be detected in both subgroups, with no significant difference between the postconditioned and the non-conditioned (IR) animals (Figure 1)
Summary
Postconditioning is a novel reperfusion technique to reduce ischemia-reperfusion injuries. In a former study of our scientific group, the postoperative systemic complications, the so-called reperfusion syndrome was investigated in a rat abdominal aorta occlusion model, and we demonstrated a significant improvement of postoperative systemic inflammatory response and redox homeostasis [9]. This present study further investigates the effect of postconditioning on muscle injury and the evolving renal dysfunction as a serious postoperative complication in a rat model of open abdominal aortic surgery. In 5 of the 10 animals postconditioning was performed. 0.3 ml blood samples were taken from the right common carotid artery 5 times in each animal: just before the onset of reperfusion and at the end of the 1st, 2nd, 3rd, 4th min of the reperfusion
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