Systemic application of carbon monoxide-releasing molecule 3 protects skeletal muscle from ischemia-reperfusion injury

Abstract

Objective: Ischemia-reperfusion (IR) is a limb- and life-threatening complication of acute limb ischemia and musculoskeletal trauma. Carbon monoxide-releasing molecules (CORMs) have recently been shown to protect microvascular perfusion and to reduce inflammation and injury in various ischemic animal models. The purpose of this study was to examine the effects of water-soluble CORM-3 on the extent of IR-induced muscle injury.

Methods: Wistar rats were randomized into three groups: sham (no ischemia), IR + CORM-3 (10 mg/kg intraperitoneally), and IR + inactive CORM-3 (iCORM-3; 10 mg/kg intraperitoneally). No-flow ischemia was induced by the application of a tourniquet to the hind limb for 2 hours; tourniquet release commenced the reperfusion phase. Both CORM-3 and iCORM-3 were injected immediately after tourniquet release. Temporal changes in microvascular perfusion, cellular tissue injury (ethidium bromide and bisbenzimide staining), and inflammatory response (leukocyte recruitment) within the extensor digitorum longus muscle were assessed using intravital video microscopy every 15 minutes for a total of 90 minutes after initiation of reperfusion. Systemic levels of tumor necrosis factor-α were also measured.

Results: Hind limb IR resulted in (1) a significant no-reflow phenomenon followed by progressive increase in microvascular perfusion deficit (21% ± 2% continuously perfused capillaries in IR vs 76% ± 4% in sham [P < .001]; 52% ± 8% nonperfused capillaries in IR vs 13% ± 2% in sham at 90 minutes of reperfusion [P < .001]), (2) tissue injury (ethidium bromide and bisbenzimide staining of 0.52 ± 0.07 in IR vs 0.05 ± 0.03 in sham at 90 minutes of reperfusion [P < .001]), (3) leukocyte recruitment (13.7 ± 0.9 adherent leukocytes/30 seconds/1000 μm² in IR vs 1.8 ± 0.5 adherent leukocytes/30 seconds/1000 μm² in sham at 90 minutes of reperfusion [P < .001]), and (4) an increase in circulating tumor necrosis factor-α levels. Systemic administration of CORM-3 (but not of iCORM-3) effectively reduced the IR-associated skeletal muscle perfusion deficits, tissue injury, and inflammatory activation.

Conclusions: CORM-3 displays potent protective and anti-inflammatory effects in an experimental model of hind limb IR, suggesting a potential therapeutic application of CORMs in treatment of ischemic conditions.