Metabolites of Tryptophane and Phenylalanine as Markers of Small Bowel Ischemia-Reperfusion Injury

Abstract

Ischemic-reperfusion injury of the small intestine is an acute clinical condition with high mortality rate. This study describes the changes in levels of phenylalanine and tryptophan metabolites in intestinal homogenates and urine samples of Wistar male rats after 60 minutes of mesenteric ischemia and different reperfusion periods (1, 24, 30 hours) in comparison with a control group without the ischemia. The ischemic-reperfusion injury was quantified by the histopathological injury index. The levels of serotonin, epinephrine, and norepinephrine were determined in the intestinal homogenate and epinephrine, vanillylmandelic acid, and the 5-hydroxyindoleacetic acid was analyzed in urine using the HPLC method. The statistically significant increased level of serotonin, epinephrine and norepinephrine were detected in the intestinal samples after 24 hours of reperfusion (p<0.01); even the most elevated serotonin level was observed after one hour of reperfusion (p<0.001). A statistically significant decreased level of vanillylmandelic acid was observed after one hour of reperfusion, but it significantly increased after 24 hours (p<0.05) in urine. The elevated level of the 5-hydroxyindoleacetic acid after one hour and 24 hours after reperfusion (p<0.05) were determined in the urine. The most significant elevated epinephrine level was observed after 24 hours of reperfusion (p<0.001) in urine. Results showed a potential role of serotonin as an early biomarker (after one hour of reperfusion) of small intestinal damaged homogenate, while the best predictor of intestinal injury in urine was epinephrine, which was elevated after 24 hours.