Effect of different periods of hyperbaric oxygen on ischemia-reperfusion injury of rat small bowel.
OBJECTIVE
To determine whether hyperbaric oxygen (HBO) could effectively protect the small intestine mucosa against an ischemic insult, according to different periods of application.


METHODS
The gut of 32 male rats was subjected to 60-min ischemia (clamping the mesenteric artery and vein); After they were further reperfused upon clamp opening during 60 min. Animal groups were as follows. GII = placed on HBO during the ischemia period; GIII = placed on HBO during reperfusion; GIV = treated with HBO throughout the ischemia-reperfusion period. Some animals (GI) did not receive HBO treatment at all and served as reference of ischemia-reperfusion injury (IR). HBO was carried out in a cylindrical acrylic chamber (2.0 ATA). Samples of small bowel were prepared for H.E staining for histological evaluations.


RESULTS
The histological injury of mucosa was significantly less when HBO was administered during the ischemia period (17.6 +/- 0.6) as compared with the IR (21.3 +/- 1.8). HBO was not effective when applied during reperfusion (23.1 +/- 2.1) or during the ischemia plus reperfusion period (18.7 +/- 1.9). The thickness of the mucosa was preserved by HBO in ischemia (327.50 +/- 30.23 microm) in comparison with the IR (172.79 +/- 5.95 microm). In the periods of reperfusion (162.50 +/- 6.05 microm) and ischemia plus reperfusion (296.49 +/- 20.01 microm) the mucosa revealed a structural injury.


CONCLUSIONS
Hyperbaric oxygen affects the ischemic insult of small bowel, being the favorable effect obtained when hyperbaric oxygen was administered early in the ischemic period.
Bertoletto
Paulo Roberto
PR
University of Grande Dourados, Mato Grosso do Sul, Brazil. bertoletto@terra.com.br
Chaves
José Carlos
JC
Fagundes
Anna Tereza Negrini
AT
Simões
Ricardo Santos
RS
Oshima
Celina Tizuko Fujiyama
CT
Simões
Manuel de Jesus
Mde J
Fagundes
Djalma José
DJ
D000818:Animals; D006931:Hyperbaric Oxygenation; D007413:Intestinal Mucosa / Q000098:blood supply* / Q000473:pathology; D007421:Intestine, Small / Q000098:blood supply* / Q000473:pathology; D019194:Ischemic Preconditioning; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000473:pathology / Q000517:prevention & control*; D013997:Time Factors