ABSTRACT
The purpose of this study was to determine whether depletion of circulating neutrophils,
using an antineutrophil monoclonal antibody (RP3), would attenuate ischemia/reperfusion
injury in rat skeletal muscle. A 3- and 5-hr period of ischemia was induced unilaterally
into the hindlimbs of rats; the isolated limbs were then reperfused for 24 hr after
ischemia. The gastrocnemius muscle was then removed, and blood was taken simultaneously.
The hematologic parameters were measured, muscle neutrophil sequestration was assessed
by myeloperoxidase (MPO) activity, free radical production was evaluated by the tissue
lipid peroxides (LPO) levels, muscle viability was assessed by tissue levels of adenosine
triphosphate (ATP) and creatine phosphate (PCr) levels, and muscle wet/dry weights
were determined. Treatment with RP3 selectively and sufficiently depleted the circulating
neutrophil population, markedly reduced MPO, and significantly attenuated LPO and
the tissue water content after both 3- and 5-hr of ischemia. After 3 hr of ischemia,
ATP and PCr levels were significantly increased by neutrophil depletion; however,
after 5 hr of ischemia, the same effect was not demonstrated. These results suggest
that neutrophil depletion after 3 hr of ischemia restrains free radical production
and edema formation, and also attenuates skeletal muscle ischemia reperfusion injury;
however, after 5 hr of ischemia, ischemic damage was so severe, that neutrophil depletion
did not reduce ischemia reperfusion injury.
