Serotonin levels in the small bowel mucosa as a marker of ischemic injury during small bowel preservation.

Of the serotonin occurring in the small bowel mucosa, 95% is present in enterochromaffine cells. The cold ischemia during small bowel transplantation results in mucosal injury and releasing of serotonin into the lumen. Because of it, the mucosal concentration of serotonin is decreasing. The aim of our study was to establish the correlation between changes in serotonin levels in small bowel mucosa during grafts preservation and cold ischemic time. Wistar rats (n= 35) weighing 322+/-18g, divided into five main groups (n= 7/group) according to the time of small bowel grafts preservation (0, 1, 6, 9, and 12 hours), were used as experimental animals. The grafts were preserved in 4 degrees C histidine-tryptophane-ketoglutarate (HTK) solution. Tissue samples for mucosal serotonin concentration measurement and for light microscopic evaluation were taken after predefined cold ischemic times. Quantitative histological assessment was made using the Park's small bowel wall injury grading scheme. The t-test for dependent samples was used for statistical analysis. The mean serotonin mucosal concentrations after 0, 1, 6, 9, and 12 hours of cold ischemic injury were 433.09+/-160.33, 402.6+/-120.53, 412.5+/-47.57 ng/mL, 190.8+/-45.88 and 145.2+/-16.78 ng/mL Statistically significant differences (p<0.05) were between 6, 9, and 12 hours of cold ischemia. Morphological changes of small bowel mucosa graded by Park's scheme after the same ischemic intervals were 0, 0.5+/-0.47, 0.97+/-0.41, 1.74+/-0.69, and 1.84+/-0.64. Statistically significant differences (p<0.05) were demonstrated between all preservation times except between 9 and 12 hours of cold ischemia. Morphological changes in small bowel mucosa correlated with cold ischemic time, as well as with serotonin mucosal concentration. These data indicate the possibility of use a serotonin concentration in small bowel mucosa as a parameter of small bowel grafts ischemic injury.