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The relationship between blood flow, development of edema and leukocyte accumulation in post-ischemic rat skeletal
A Sirsjö1, P Söderkvist, U Gustafsson
1Department of Occupational Medicine, Faculty of Health Sciences, University of Linköping, Sweden.
Abstract:
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.
Insights
Polymorphonuclear leukocytes (PMNLs) do not significantly impact blood flow or edema after ischemia. In severe ischemia, PMNLs correlated with edema only in the early reperfusion phase, suggesting they are not the primary cause.
Area of Science:
- Physiology
- Pathology
- Biochemistry
Background:
- Ischemia-reperfusion injury in skeletal muscle is a significant clinical concern.
- The role of polymorphonuclear leukocytes (PMNLs) in post-ischemic complications like reduced blood flow and edema is debated.
Purpose of the Study:
- To investigate the relationship between blood flow, edema, and PMNL infiltration in rat skeletal muscle following temporary ischemia.
- To determine if PMNLs are a major contributor to the 'no-reflow' phenomenon and edema formation during reperfusion.
Main Methods:
- A tourniquet model was used to induce temporary ischemia in rat hindlimbs for 3 or 4 hours.
- Blood flow was measured using the xenon washout method.
- Edema was assessed by total water content, and PMNLs were quantified via myeloperoxidase activity.
Main Results:
- Severe ischemia (4 hours) led to a 'no-reflow' phenomenon during early reperfusion, indicating restricted blood flow.
- No significant correlation was found between PMNL numbers and restricted blood flow.
- A positive correlation between PMNLs and edema was observed only at 0.5 hours of reperfusion after 4 hours of ischemia.
Conclusions:
- PMNLs do not appear to be the primary drivers of reduced blood flow in the early reperfusion phase after skeletal muscle ischemia.
- While PMNLs correlate with edema in specific early reperfusion conditions, they are unlikely to be the major cause of edema formation post-ischemia.