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Persistent neutrophil (PMN) activation 24 hr after ischemia and reperfusion
S T Summers1, L E Wyatt, J A Freischlag
1Department of Surgery, Wadsworth VA, Los Angeles, California.
Abstract:
Neutrophils have been implicated as mediators of the reperfusion injury which occurs in skeletal muscle after ischemia. The purpose of this study is to determine if PMN chemotaxis occur 24 hr after an ischemic injury followed by reperfusion. Rabbit hindlimbs were made ischemic by clamping the right iliac and femoral arteries for 2 or 3 hr after ligating all pelvic collaterals. The limb was then reperfused by removing the clamps. After 24 hr of reperfusion, blood samples were drawn from the carotid artery and right iliac vein. Serum and PMN were isolated from each blood sample. Chemotaxis, as determined by migration across a filter, was measured in each group. One-way analysis of variance demonstrated a significant increase in chemotaxis in PMN isolated from the venous effluent of hind limbs which had undergone 3 hr of ischemia and 24 hr of reperfusion. PMN isolated from the carotid artery of the same animals had significantly less chemotactic activity. There were no significant differences from control in PMN chemotaxis in specimens from sham animals or animals exposed to 2 hr of ischemia and 24 hr of reperfusion. Those rabbits which had undergone 3 hr of ischemia had a clinically stiff and edematous hindlimb, whereas those which had undergone 2 hr of ischemia and the sham animals had a normal hindlimb after 24 hr of reperfusion. PMN isolated from the venous effluent of an ischemic limb after 3 hr of ischemia and 24 hr of reperfusion demonstrated increased chemotaxis while systemic arterial PMN from the same animals showed no more chemotaxis than control cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Neutrophil (PMN) chemotaxis increased significantly in rabbit hindlimbs 24 hours after 3 hours of ischemia and reperfusion. This localized increase in PMN activity suggests a role in skeletal muscle reperfusion injury.
Area of Science:
- Biomedical Science
- Surgical Research
- Inflammation Research
Background:
- Neutrophils (PMN) are implicated in skeletal muscle reperfusion injury following ischemia.
- Understanding PMN activity post-ischemia is crucial for developing therapeutic strategies.
Purpose of the Study:
- To investigate polymorphonuclear leukocyte (PMN) chemotaxis in skeletal muscle 24 hours after ischemic injury and reperfusion.
- To determine if PMN chemotaxis is localized to the ischemic limb or systemic.
Main Methods:
- Rabbit hindlimbs underwent 2 or 3 hours of ischemia followed by 24 hours of reperfusion.
- Blood samples were collected from the carotid artery and iliac vein.
- PMN chemotaxis was measured using a filter migration assay.
Main Results:
- Significant increase in PMN chemotaxis observed in venous effluent from hindlimbs subjected to 3 hours of ischemia and 24 hours of reperfusion.
- PMN from the carotid artery of the same animals showed significantly less chemotactic activity.
- No significant differences in PMN chemotaxis were found in sham animals or those with 2 hours of ischemia.
Conclusions:
- A 3-hour ischemic insult followed by 24-hour reperfusion leads to increased PMN chemotaxis localized to the affected limb.
- This localized increase in PMN chemotaxis may contribute to skeletal muscle reperfusion injury.
- Shorter ischemia durations (2 hours) did not result in significant changes in PMN chemotaxis.