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 D-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 D-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. (C) 2002 Elsevier Science Ltd and ISBI. All rights reserved.