title: Effect of acute, slightly increased intra-abdominal pressure on intestinal permeability and oxidative stress in a rat model.
abstract: BACKGROUND
  Intra-abdominal hypertension (IAH) is known as a common, serious complication in critically ill patients. Bacterial translocation and permeability changes are considered the pathophysiological bases for IAH-induced enterogenic endotoxemia and subsequent multiorgan failure. Nevertheless, the effects of slightly elevated intra-abdominal pressures (IAPs) on the intestinal mucosa and the associated mechanisms remain unclear.
  
  
  METHODS
  To investigate the acute effects of different nitrogen pneumoperitoneum grades on colonic mucosa, male Sprague-Dawley rats were assigned to six groups with different IAPs (0 [control], 4, 8, 12, 16, and 20 mmHg, n = 6/group). During 90 min of exposure, we dynamically monitored the heart rate and noninvasive hemodynamic parameters. After gradual decompression, arterial blood gas analyses were conducted. Thereafter, structural injuries to the colonic mucosa were identified using light microscopy. Colon permeability was determined using the expression of tight junction proteins, combined with fluorescein isothiocyanate dextran (FD-4) absorption. The pro-oxidant-antioxidant balance was determined based on the levels of malondialdehyde (MDA) and antioxidant enzymes.
  
  
  RESULTS
  IAH significantly affected the histological scores of the colonic mucosa, tight junction protein expression, mucosal permeability, and pro-oxidant-antioxidant balance. Interestingly, elevations of IAP that were lower than the threshold for IAH also showed a similar, undesirable effect. In the 8 mmHg group, mild hyponatremia, hypocalcemia, and hypoxemia occurred, accompanied by reduced blood and abdominal perfusion pressures. Mild microscopic inflammatory infiltration and increased MDA levels were also detected. Moreover, an 8-mm Hg IAP markedly inhibited the expression of tight junction proteins, although no significant differences in FD-4 permeability were observed between the 0- and 8-mmHg groups.
  
  
  CONCLUSIONS
  Acute exposure to slightly elevated IAP may result in adverse effects on intestinal permeability and the pro-oxidant-antioxidant balance. Therefore, in patients with critical illnesses, IAP should be dynamically monitored and corrected, as soon as possible, to prevent intestinal mucosal injury and subsequent gut-derived sepsis.
authors.affiliation: Department of Intensive Care Unit, Peking University Third Hospital, Haidian District, Beijing, P.R. China.
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Leng
authors.affiliation: Laboratory Animal Center, Peking University Health Science Center, Haidian District, Beijing, P.R. China.
authors.forename: Kuo
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Intensive Care Unit, Peking University Third Hospital, Haidian District, Beijing, P.R. China.
authors.forename: Jie
authors.initials: J
authors.lastname: Fan
authors.affiliation: Department of Intensive Care Unit, Peking University Third Hospital, Haidian District, Beijing, P.R. China.
authors.forename: Min
authors.initials: M
authors.lastname: Yi
authors.affiliation: Department of Intensive Care Unit, Peking University Third Hospital, Haidian District, Beijing, P.R. China.
authors.forename: Qinggang
authors.initials: Q
authors.lastname: Ge
authors.affiliation: Department of Central Laboratory, Peking University Third Hospital, Haidian District, Beijing, P.R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Gastroenterology, Peking University Third Hospital, Haidian District, Beijing, P.R. China.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Intensive Care Unit, Peking University Third Hospital, Haidian District, Beijing, P.R. China.
authors.forename: Gaiqi
authors.initials: G
authors.lastname: Yao
mesh_terms: D034841:Abdominal Cavity / Q000382:microbiology / Q000503:physiopathology; D000818:Animals; D018988:Bacterial Translocation / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism / Q000503:physiopathology; D059325:Intra-Abdominal Hypertension / Q000150:complications*; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D008315:Malondialdehyde