Reperfusion injury

Reperfusion injury refers to damage to tissuecaused when bloodsupply returns to the tissue after a period of ischemia. The absence of oxygenand nutrientsfrom blood creates a condition in which the restoration of circulationresults in inflammationand oxidativedamage from the oxygen rather than restoration of normal function.

The damage of reperfusion injury is due in part to the inflammatory responseof damaged tissues. White blood cellscarried to the area by the newly returning blood release a host of inflammatory factorssuch as interleukinsas well as free radicalsin response to tissue damage (Clark, 2005). The reintroduction of oxygen with restored blood flow forms within cellsthat damage cellular proteins, DNA, and the plasma membrane. Damage to the cell's membrane may in turn cause the release of more free radicals. Leukocytes may also build up in small capillaries, obstructing them and leading to more ischemia (Clark, 2005).

Reperfusion injury plays a part in the brain's ischemic cascade, which is involved in strokeand brain trauma. Repeated bouts of ischemia and reperfusion injury also are thought to be a factor leading to the formation and failure to healof chronic woundssuch as pressure soresand diabetic foot ulcers(Mustoe, 2004). Continuous pressure limits blood supply and causes ischemia, and the inflammation occurs during reperfusion. As this process is repeated, it eventually damages tissue enough to cause a wound(Mustoe, 2004).

References

1. Clark WM. 2005. Reperfusion Injury in Stroke. Emedicine.com.
2. Mustoe T. Understanding chronic wounds: a unifying hypothesis on their pathogenesis and implications for therapy. The American Journal of Surgery, Volume 187, Issue 5, Supplement 1, May 2004, Pages S65-S70.

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It uses material from the http://en.wikipedia.org/wiki/Reperfusion+injury Wikipedia article Reperfusion injury.