Protective Effects Of 4-DAMP Preconditioning On Rats' Gut Barrier Injury In Cardiopulmonary Bypass

Objective: To investigate the protective effects and underlying mechanisms of 1,1-Dimethyl-4-diphenylacetoxypiperidinium iodide(4-DAMP)preconditioning on rats' gut barrier injury in cardiopulmonary bypass.Methods: 96 male SD rats weighting of 350g~450g were randomly divided into 4 groups(n=24):sham operated group(group S),cardiopulmonary bypass group(group C),carbamyl-?-methylcholine chloride+4-DAMP pre-conditioning group(group M)and 4-DAMP pre-conditioning group(group D).Each group was anesthetized by 10% chloral hydrate(0.35ml/100g)and mechanically ventilated with tracheal intubation and small animal ventilator.Femoral artery,femoral vein,caudal artery and jugular vein were cannulated respectively.Established the cardiopulmonary bypass model after anesthesia in group CPB.In group M,SD rats were injected 6?g/kg carbamyl-?-methylcholine chloride and(1.25×10-5)mg/kg 4-DAMP in femoral vein before establishing the model of cardiopulmonary bypass.In group D,SD rats were injected(1.25×10-5)mg/kg 4-DAMP in femoral vein before establishing the model of cardiopulmonary bypass.Hemodynamic indexes and blood samples for IL-6,TNF-?,D-Lactate(D-Lac)and intestinal type fatty acid-binding protein(I-FABP)measurements were collected during the following time points: T0(before pretreatment,before transferring),T1(transferring instantly),T2(2h after CPB)and T3(6h after CPB).Then rats in each group were observed and sacrificed.Histopathological changes in the intestinal tissue was observed by HE staining.Collected blood samples at the inferior vena cava and taked mesenteric lymph nodes(MLN),liver,lung,and kidney of tissuefor bacterial culture,calculating distant organs translocation frequency.Western blotting method to detect intestinal tissue occluding and ZO-1 protein expression levels.Results: 1.Pathological observation showed that the structure of intestinal mucosa in group S was regularly,the villus were seen clearly and the brush borders were normal.In C group and M group,intestinal mucosa edema,neutrophil and lymphocyte infiltration were seen,Some of the villus were broken off with the inherent layer capillary congestion.In D group,the intestinal mucosal injury was better than C group and M group,only seen partial villous edema,intestinal cortex and lamina propria of moderate resolution,with a few of inflammatory cells infiltration.2.The changes concentration of serum TNF-? and IL-6: Compared with group S,the serum TNF-? and IL-6 concentrations were significantly increased in group C,M and D(p<0.05).Compared with group C and group M,the serum TNF-? and IL-6 concentrations of group D were significantly reduced(p<0.05).There was no significant difference in serum TNF-? and IL-6 concentrations at each time point between group C and group M(p>0.05).3.The changes concentration of serum D-Lac and I-FABP: Compared with group S,the serum D-Lac and I-FABP concentrations were significantly increased in group C,M and D(p<0.05).Compared with group C and M,the serum D-Lac and I-FABP concentrations of group D were significantly reduced(p<0.05).There was no significant difference in serum D-Lac and I-FABP concentrations at each time point between group C and group M(p>0.05).4.The rate of bacterial translocation: Compared with group S,the rate of bacterial translocation to animal organs were significantly increased in group C,M and D(p <0.05).Compared with group C and M,the rate of bacterial translocation to animal organs of group D were significantly reduced(p<0.05).There was no significant difference in the rate of bacterial translocation to animal organs between group C and group M(p>0.05).5.The changes expressions of Occludin and ZO-1: Compared with group S,the expressions of Occludin and ZO-1 in intestinal tissues were significantly increased in group C,M and D(p<0.05).Compared with group C and group M,the expressions of Occludin and ZO-1 in intestinal tissues of group D were significantly reduced(p<0.05).There was no significant difference in the expressions of Occludin and ZO-1 in intestinal tissues at each time point between group C and group M(p>0.05).Conclusion: 1.4-DAMP can reduce the damage of CPB on the intestinal barrier in SD rats.2.The mechanism may be related to up regulation of Occludin,ZO-1 and other tight junction protein and reduce the release of inflammatory factors.