The effect of 100% oxygen on intestinal preservation and recovery following ischemia-reperfusion injury in rats.
OBJECTIVE
Inhalation of oxygen improves the hemodynamic status and attenuates the inflammatory response after intestinal ischemia-reperfusion (IR). Yet, the use of hyperoxia is hindered by concerns that it could exacerbate reperfusion injury by increasing free radical formation. We examined the effect of hyperoxia on enterocyte turnover and intestinal preservation and rehabilitation following IR injury in rats.


METHODS
Animal study.


METHODS
Research laboratory.


METHODS
Male Sprague-Dawley rats.


METHODS
Animals were assigned to four experimental groups: 1) Sham rats underwent laparotomy without vascular occlusion and breathed air, 2) Sham-oxygen rats underwent laparotomy without vascular occlusion and breathed 100% oxygen, 3) IR rats underwent occlusion of the superior mesenteric artery and portal vein for 30 minutes and breathed air, and 4) IR group treated with oxygen (IR-O2)rats underwent IR and breathed 100% oxygen starting 10 minutes before and continued for the first 6 hours after reperfusion. Intestinal structural changes, enterocyte proliferation, and enterocyte apoptosis were determined 24 hours after IR.


RESULTS
In IR rats, breathing 100% oxygen resulted in a significant decrease in Park's injury score in the ileum (p < 0.05 from untreated IR rats). Rats treated with oxygen also demonstrated a significant increase in mucosal weight (p < 0.05) and mucosal DNA (p < 0.05) in the jejunum and ileum, and an increase in villus height (p < 0.01), and crypt depth (p < 0.05) in the ileum. Enterocyte proliferation (assessed by bromodeoxyuridine uptake) was significantly decreased in the jejunum and ileum in untreated IR rats. Oxygen therapy increased enterocyte proliferation in the ileum, and diminished both the apoptosis index and Bax gene expression in the jejunum and ileum (p < 0.05). Plasma thermochemiluminescence oxidizability assay revealed significantly higher thermochemiluminescence ratios in IR group treated with oxygen than in untreated IR rats (p < 0.05) at 6 hours postreperfusion suggesting a significantly lower prior in vivo molecular oxidation.


CONCLUSIONS
Hyperoxia reduces small bowel injury, accelerates enterocyte turnover, and improves intestinal rehabilitation after IR.
Sukhotnik
Igor
I
Departmentsof Pediatric Surgery, Bnai Zion Medical Center, Haifa, Israel. igordr@internet-zahav.net
Brod
Vera
V
Lurie
Michael
M
Rahat
Michal A
MA
Shnizer
Sergei
S
Lahat
Nitza
N
Mogilner
Jorge G
JG
Bitterman
Haim
H
D000818:Animals; D020895:Enterocytes / Q000187:drug effects / Q000502:physiology*; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000098:blood supply*; D008297:Male; D010100:Oxygen / Q000008:administration & dosage* / Q000378:metabolism; D010102:Oxygen Inhalation Therapy; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism / Q000534:rehabilitation / Q000628:therapy*
D010100:Oxygen