Experimental study of serum SM22 in the diagnosis of acute intestinal ischemia

Objective To evaluate smooth muscle protein of 22 kDa (SM22) in the diagnosis of acute intestinal ischemia. Methods 96 healthy adult SD rats were evenly divided into experimental group and control group, with each group subdivided into 6 subgroups, subject respectively to superior mesenteric artery ligation or sham operation. The venous blood samples were extracted from each group rats′ right heart at 0.5, 1, 2, 4, 8, 12 h after the operation, for SM22 testing and small intestines tissues for direct immunofluorescence staining of SM22. Results The serum SM22 concentration reached a peak at 4 h(265±15)mg/L, then gradually decreased (P<0.05). The I-FABP was mainly expressed in the epithelium of intestinal mucosa. During the 4 hours of intestinal ischemia, The number of SM22 positive particles did not change. After 4 hours, the number of SM22 positive granules had gradually decreased compared with the control group (all P<0.05). Conclusion SM22 mainly exists in the smooth muscle of intestinal, during the ischemic necrosis of the intestinal muscle layer SM22 leaks into blood stream, resulting in high serum levels of SM22 facilitating early diagnosis of acute intestinal ischemia. Key words: Ischemia; Diagnosis; Smooth muscle protein 22