The relationship between blood flow, development of edema and leukocyte accumulation in post-ischemic rat skeletal muscle.

The relationship between blood flow (xenon washout method), edema formation (percent total water content), and the number of polymorphonuclear leukocytes (PMNLs), as measured by the level of the enzyme myeloperoxidase, has been investigated in post-ischemic skeletal muscle of rats. A tourniquet model of temporary, complete ischemia of one hindlimb for 3 or 4 hours was used. Biopsies were taken after 0.5, 5 and 12 hours of reperfusion (6 experimental groups) and from a control group that had received only anesthesia. After 4 hours, but not 3 hours of ischemia there was a restricted blood flow during the early reperfusion phase, the "no-reflow" phenomenon, indicating severe ischemia. There was no significant accumulation of PMNLs in the skeletal muscle nor was there a correlation between the number of PMNLs in the post-ischemic muscle and the restricted bloodflow. With 4 hours of ischemia and 0.5 hours of reperfusion there was a statistically significant, positive correlation between the number of PMNLs and the amount of edema; no such correlation was evident in either of the other groups. These results suggest that PMNLs are not the major cause of reduced bloodflow or of edema in the early reperfusion phase after total ischemia.