The influence of apoptosis of mucosal epithelial cells on intestinal barrier integrity after scald in rats

Objective: To study the influence of apoptosis of intestinal epithelial cells occurring as a result of reperfusion after burn shock on the intestinal barrier. Methods: Fifty Wistar rats were subjected to a 30% TBSA full thickness burn, and normal saline (40 ml/kg) was given intraperitoneally immediately after the injury (group A). Ten rats served as a sham control group. The experimental group B consisted of 50 rats with identical injuries, but the normal saline was not given until 6 h after the injury. Apoptosis of intestinal epithelial cells was verified by DNA fragmentation, DNA agarose gel electrophoresis, TUNEL and electron microscope (EM), and DNA fragmentation rate was expressed as ap%. The -lactic acid in portal vein blood and intestinal diamine oxidase (DAO) were determined to evaluate the permeability and integrity of intestinal mucosal epithelium. Results: The ap% of intestinal epithelium group B was higher than in that of group A (P<0.05 or 0.01), and its amplitude peaked at 12 h for both groups. Typical DNA ladder pattern was seen in electrophoresis in both groups. Apoptotic cells were discerned on the tips of the ileal villi at 3 h postscald by TUNEL and EM in the group B, and they appeared earlier than in the group A. There was a significant positive correlation between the ap% and the level of -lactic acid (group A: r=0.817, P<0.05; group B: r=0.727, P<0.05). On the other hand, a significant negative correlation was found between the ap% and the DAO values (group A: r=−0.937, P<0.01; group B: r=−0.836, P<0.05). Conclusion: Apoptosis occurred in enterocytes after scald injury this pathological change might contribute to a breach of integrity of intestinal epithelium, leading to a compromise in its barrier function. Delayed fluid resuscitation might lead to an earlier and higher degree of apoptosis of the intestinal epithelial cells.