Objective: Portal hypertension is a hyperdinamic circulation disorder characterized by high portal venous pressure. The aim of the study is to reveal oxidative damage measuring nitric oxide levels and myeloperoxidase, xanthine oxidase, superoxide dismutase and glutathione peroxidase enzyme activities in small intestine and colon tissues of rats undergo portal hypertensive surgery.

Material and Methods: 25 male Sprague-Dawley rats weighing 200-250 g were included in the study and they were separated into two groups: Group I (Sham) (n=13), Group II (Portal hypertension) (n=12). Portal hypertension was induced in group II by the partial ligation of portal vein for 8 weeks. The level of nitric oxide, enzyme activities of myeloperoxidase, xanthine oxidase, superoxide dismutase and glutathione peroxidase were measured spectrophotometrically in all groups.

Results: Nitric oxide levels of the small intestine and colon tissues in group II are significantly higher than those in the sham group (p<0.05). Small intestine and colon myeloperoxidase, small intestine xanthine oxidase enzyme activities in group II were higher than in sham group. Small intestine, colon superoxide dismutase and small intestine glutathione peroxidase enzyme activities in group II were lower than in sham group. However, these differences were not statistically significant.

Conclusions: Increased nitric oxide levels in small intestine and colon tissues in portal hypertension may lead to such complications as vasodilatation and varicose vein bleeding due to vasodilatation. Neutrophil invasion into small intestine and colon tissues may be the cause of the increase in myeloperoxidase activity. It is also considered that increased xanthine oxidase activity in small intestine tissues may be associated with bacterial translocation and that this increase may lead to superoxide anion accumulation. Toxic metabolites such as increased superoxide anion and ammonia may play a part in the suppression of antioxidant defense systems. However, we concluded that with comprehensive studies we can obtain statistically significant results and enlighten biochemical mechanisms in order to clarify oxidant and antioxidant condition in the small intestine and colon tissues when portal hypertension develops.