MICROSURGICAL MODEL OF ISCHEMIA-REPERFUSION IN RAT MUSCLE - EVIDENCE OF FREE-RADICAL FORMATION BY SPIN-TRAPPING

The purpose of developing the experimental model described in this stu dy was to verify the hypothesis that free radicals are formed during i schemia-reperfusion of skeletal muscle. Spin trapping technique, along with electron spin resonance spectroscopy (ESR), directly indicates t hat presence of reactive radicals, which are widely considered to be i mportant in tissue injury. The experimental model was a rat pedicled r ectus femoris muscle flap. The femoral artery and vein were cannulated to inject the ''spin trap'' and collect the effluent flow. The spin t rap agent was phenyl-t-butyl nitrone (PBN) and Hank's balanced salt so lution. Three injections and collections were made: a) before ischemia ; b) after ischemia of 15, 30, 60, 120, and 180 minutes, but before bl ood flow had been restored; and c) after blood flow had been restored. No ESR signal was detected either before the ischemic period or after only 15 minutes of ischemia. PBN radical adducts were detected after 30, 60, 120, and 180 minutes of ischemia. A similar signal was detecte d when PBN was injected during reperfusion 10 minutes after the ischem ic periods. The study demonstrated the presence of free radicals in an in vivo intact skeletal muscle ischemia-reperfusion model. (C) 1994 W iley-Liss, Inc.