Inosine attenuates tourniquet-induced skeletal muscle reperfusion injury.
BACKGROUND
Adenosine attenuates skeletal muscle reperfusion injury, but its short half-life in vivo limits potential therapeutic benefits. The aim of this study was to ascertain whether inosine, a stable adenosine metabolite, modulates skeletal muscle reperfusion injury.


METHODS
C57BL/6 mice were randomized (8-10 per group) to six groups: time controls; inosine (100 mg/kg) before anesthesia; 2 h of bilateral tourniquet hindlimb ischemia; I/R (2 h of bilateral tourniquet hindlimb ischemia, 3 h of reperfusion); inosine (100 mg/kg) before I/R; drug vehicle before I/R. Serum tumor necrosis factor (TNF)-alpha and macrophage inflammatory protein (MIP)-2 were measured before ischemia and at the end of reperfusion. Tissue edema was determined by wet/dry weight ratios. Tissue leucosequestration was assessed by the myeloperoxidase (MPO) content.


RESULTS
At the end of reperfusion, inosine pretreatment resulted in lower MPO levels in muscle (P = 0.02) and lung (P = 0.0002) than saline pretreatment. Similarly, muscle (P = 0.04) and lung (P = 0.02) wet/dry ratios were significantly reduced with inosine but not with saline pretreatment. At the end of reperfusion, serum proinflammatory cytokine levels (TNF-alpha and MIP-2) were significantly reduced (P < 0.05) compared to preischemia levels following inosine pretreatment but not saline pretreatment. Ischemia alone did not alter any of the parameters assessed.


CONCLUSIONS
These findings demonstrate that pretreatment with inosine attenuates the local and systemic proinflammatory responses associated with skeletal muscle reperfusion injury.
Wakai
A
A
Department of Academic Surgery, Cork University Hospital, Cork, Republic of Ireland.
Winter
D C
DC
Street
J T
JT
O'Sullivan
R G
RG
Wang
J H
JH
Redmond
H P
HP
D000818:Animals; D054426:Chemokine CXCL2; D018925:Chemokines / Q000097:blood; D004195:Disease Models, Animal; D004487:Edema / Q000188:drug therapy / Q000378:metabolism; D007288:Inosine / Q000494:pharmacology*; D008168:Lung / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism*; D018384:Oxidative Stress; D009195:Peroxidase / Q000032:analysis; D011654:Pulmonary Edema / Q000378:metabolism; D015427:Reperfusion Injury / Q000188:drug therapy* / Q000378:metabolism; D014111:Tourniquets / Q000009:adverse effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D054426:Chemokine CXCL2; D018925:Chemokines; C404915:Cxcl2 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D007288:Inosine; D009195:Peroxidase