| OBJECTIVE1)To create a model of acute intestinal ischemia-reperfusion injury in rabbits so as to determine suitable blocking duration of superior mesenteric arteries (SMA).2) To determine the suitable duration and mechanisms of postconditoning has protective effect on acute intestinal ischemia-reperfusion injury in rabbitsMETHODIntestinal ischemia-reperfusion was induced in rabbits.Seventy rabbits were divided into 5 groups as groups A,B,C,D,and E, based on the different blocking durations of SMA for 0,15,30,45,and 60minutes,respectively,with 14 rabbits in each group. Eight of the rabbits in each group were detected for serum levels of MDA 2h after recovery of blood supply, the changes of histomorphology of small intestinal tissues observed light-microscopically. The other six rabbits in each group were used to observe the 24 h-,48 h-and 72 h-survival rates after the blockage of SMA. The two different ways of ischemic postconditioning were applied to the rabbits, injuried by ischemic reperfusion. The intestinal injury was assayed by detecting the concentration of MDA and MPO in serum and intestinal tissues after the reserved time.RESULTSThe survive rate was over 83.3% in groups A, Band C.Serum levels of MDA and score of injury of intestinal mucosa were significantly higher in groups C, D and E than that in group A(F=12.13-280.24;P<0.01).Undergoing 30mins of ischemia and 120mins of reperfusion cause dramatically injuries in rabbit intestines.After 120mins reperfusion, the concentration of MDA were significantly higher in each group than that in sham group,(t=19.76～49.84,P<0.01).this suggest the existence of ischemia-reperfusion injury. Although intestinal tissue levels of MDA in IpostCl group is higher than that in sham group and lower than that in I/R group(t=49.84,P<0.01).The 3 cycles of 30 sec ischemia and 30 sec reperfusion before reperfusion reduce the cell lipid peroxidation and cell injury to a certain extent. The concentration of MDA in IpostC2 group is higher than that in I/R group, but there is no different between them(t=1.86,P>0.05).This suggests that the 3 cycles of 60 sec ischemia and 60 sec reperfusion before reperfusion has no protective effect on ischemia intestinal tissues.After 120mins reperfusion, the concentration of MPO were significantly higher in each group than that in sham group,(t=19.76～49.84,P<0.01).this further suggest the existence of ischemia-reperfusion injury. Although intestinal tissue levels of MDA in IpostCl group is higher than that in sham group and lower than that in I/R group(t=3.54,P<0.01).The 3 cycles of 30 sec ischemia and 30 sec reperfusion before reperfusion reduce the neutrophil infiltration and cell injury to a certain extent. The concentration of MPO in IpostC2 group is higher than that in I/R group, but there is no significantly different between them(t=1.86,P>0.05).This also suggests that the 3 cycles of 60 sec ischemia and 60 sec reperfusion before reperfusion has no protective effect on ischemia intestinal tissues.The serum concentration of MDA and MPO is significantly increased in I/R group and postconditiong groups compared with sham group (P<0.01).The 3 cycles of 30 sec ischemia and 30 sec reperfusion can reduce the generation of MDA and MPO(P<0.01),while 3 cycles of 60 sec ischemia and 60 sec reperfusion can not bring about the protective effect(p>0.05).After 120mins reperfusion without control, score of injury of intestinal mucosa in I/R group (3.1±0.72)was significantly higher than that in sham group(0.60±0.70),there was a significant difference.(t=24.79, P＜0.01),thus ischemia-reperfusion result in significant intestinal pathology injury. Score values of injury of intestinal mucosa in IpostC1 group(1.8±0.88) was significantly higher than that in sham group and lower than that in I/R group(t=3.62, P<0.01),these suggests the 3 cycles of 30 sec ischemia and 30 sec reperfusion can attenuate the damage caused by ischemia-reperfusion injury of intestinal pathology.CONCLUSION1.The suitable duration for creating a model of acute SMA ischemia-reperfusion injury in small bowel is ischemia for 30minutes and reperfusion for 2 hours.2.IpostC1 can attenuate intestinal ischemic reperfusion injury by reducing the levels of MDA and MPO.3.IpostC1 can effectively reduce intestinal lipid peroxidation and inflammatory infiltration induced by ischemia-reperfusion.
|
PDF Full Text Request