Effects of hydrogen peroxide scavenger Catalase on villous microcirculation in the rat small intestine in a model of inflammatory bowel disease

This study was conducted to quantify the effect of systemic Catalase, a hyd rogen peroxide scavenger, on vilious microcirculation in the inflamed small intestine of the rat. Intestinal inflammation was induced with s.c, applic ation of Indomethacin. Intravital fluorescence microscopy and FITC-labeled erythrocytes were used to quantify erythrocyte velocity and arteriolar diam eter in the main arteriole of the villi in the terminal ileum following i.v . application of Catalase in the inflamed intestine, and the blood flow was calculated. Control groups were formed for Ringer's lactate, Catalase and Indomethacin, respectively. We found that villous blood flow was significan tly increased in the in the inflamed intestine. Application of Catalase led to a significant decrease in villous perfusion, but had no effect in the c ontrol group. The increase in villous blood flow was accompanied by changes in the diameter of the main arteriole. This effect on arteriolar diameter was reversed by i.v. Catalase. Our results provide evidence that systemic a pplication of Indomethacin leads to vasodilatation of the main arteriole of the villus in the rat ileum and hyperemia in the mucosa. Hyperemia and the vascular diameter of the main arteriole were significantly reduced by H2O2 -scavenger Catalase, suggesting that endogenous H2O2 may be one of the medi ators of hyperemia in the mucosa in this animal model of intestinal inflamm ation. (C) 2000 Academic Press.