Background
The pathways leading to regeneration of injured epithelial cells after transient ischemia remain incompletely defined. Accordingly, we set out to study the mechanism of epithelial injury and regeneration in a standardized model of acute mesenteric ischemia-reperfusion (I/R) injury.

Material and Methods
Anaesthetized rats were exposed to sham operation or 45 min of intestinal ischemia, with or without 30 min of reperfusion. Additional groups were treated with AcPepA (4 mg/kg iv.), a synthetic C5a antagonist peptide before ischemia or reperfusion. The proliferative capacity of the epithelium was determined by the degree of injury and proliferating cell nuclear antigen (PCNA) staining. The number of C5a receptor-positive PMN leukocytes (C5L2 staining), CD68 and CD204-positive macrophages and hypoxia-inducible factor 1 alpha (HIF-