Experimental Study On Phenotypic Characteristics Of Sepsis Myocardial Injury Induced By Different Strains

Objective To explore the changes and differences of related indicators of sepsis induced myocardial injury between Gram-positive bacteria and Gram-negative bacteria in rats in vivo,so as to provide a certainexperimental basis for the early identification of sepsis pathogens.Methods 105 male SD rats were randomly divided into control（NC）group,gram-positive bacterial sepsis（SA）group and Gram-negative bacterial sepsis（EC）group.SA group:3ml heat inactivated Staphylococcus aureus was injected intraperitoneally,[low dose（Sal）:5.2x10¹²CFU/kg,middle dose（Sam）:7.35x10¹²CFU/kg,high dose（SAH）:9.45×10¹²CFU/kg];EC Group:3ml heat inactivated Escherichiacoli[(low dose（ECM）:1.05x10¹²CFU/kg,middle dose（ECM）:1.26x10¹²CFU/kg,high dose（ECH）:1.47×10¹²CFU/kg];NC group:Intraperitoneal injection of physiological saline.Myocardial blood sampleswere collected at 6 h 12 h,24 h,48 h and 72 h after the model was successfully established.The contents of c Tn I,TNF-αand IL-1βwere detected by ELISA kit,and the myocardium was stained with HE at thecorresponding time point.The expression levels of PINK1 and Parkin were detected at 24 h,48 h and 72 h.Results（1）compared with normal saline group,rats in SA group and EC group died after infection,and the mortality increased in a concentration dependent manner.（2）Compared with the normal saline group,the sepsis score of SA group and EC group increased significantly from 6 h（P<0.05）,and the sepsis score of SA group was higher than that of EC group at each time point（P<0.05）.（2）Serum c Tn I levels in SA and EC groups began to increase at 6 h,peaked at 24 h,and decreased at 48 h（P<0.05）.（3）TNF was detected in serum of SA group and EC group TNF-αAnd IL-1βThe peak value was reached at 6 h,and began to decrease at 12 h,and decreased significantly at 48 h and 72 h compared with 12 h（P<0.05）.（4）After he staining,there were pathological differences in the myocardial tissue of each dose group in SA group and EC group,and the inflammatory infiltration in SA group was stronger than that in EC group 24hours ago,which was higher than that in NC group.The pathological scores in ECL and ECM groups began to increase significantly at 24 hours（P<0.05）,and those in ECH,SAL,SAM and SAH groups began to increase significantly at 12 hours（P<0.05）;Compared with ECL group,the pathological score of ECM group increased significantly at 24 h（P<0.05）;Compared with ECM group,the pathological score of ECH group increased significantly at 12 h（P<0.05）;Compared with Sal group,the pathological score of Sam group increased significantly at 24 h（P<0.05）;Compared with Sam group,the pathological score of SAH group increased significantly at 12 h（P<0.05）.（5）PINK1 and parkin protein were expressed in mitochondria.The expression levels of PINK1 and parkin protein in SA group and EC group increased from 24 h,and were higher than those in NC group（P<0.05）,and reached the peak at 48 h（P<0.05）;The protein expression levels of PINK1 and parkin decreased at 72 h,but still higher than that at24 h（P<0.05）.Conclusion In the sepsis model induced by intraperitoneal injection of heat inactivated gram positive bacteria and Gram-negative bacteria,myocardial injury caused by Gram-positive bacteria bacteria was more severe than that caused by Gram-negative bacteria,the expression of tnf-αand IL-1βincreased in the early stage,and then decreased in time-dependent manner.The activity of cardiac troponin I and mitochondrial autophagy increased first and then decreased.