Study On Related Mechanisms Of Heart Failure In Dogs With Multiple Organ Dysfunction Syndrome Caused By Sepsis

Objective: By constructing the model dog of multiple organ dysfunction syndrome(MODS)caused by sepsis,the change trend of vital signs and the change trend of relevant detection indexes(homocysteine,myocardial enzyme,myocardial enzyme isoenzyme,urea nitrogen and creatinine)during heart failure were studied,and the changes of vital signs and laboratory indexes were monitored and evaluated.If early identification and timely intervention can be achieved in the process of occurrence and development of diseases,it is of great significance for these diseases.Understanding the changes at different time points can help us timely intervene the time point of heart failure caused by sepsis,affect the outcome of the disease,reduce the deterioration rate and strive for survival.At the same time,the expression of matrix metalloproteinase-9(MMP-9)and its endogenous inhibitor tissue inhibitor of metalloproteinase-1(TIMP-1)in left ventricular myocytes and the expression of miRNAs related subtypes during heart failure in this model dog were used to further verify whether these genes are involved in the occurrence of heart failure caused by sepsis,Help us better understand the relevant mechanisms of heart failure.Because it is impossible to take sample human myocardium before death when sepsis causes heart failure.through the pathological sampling of myocardium,kidney and liver of model dogs,we can observe the acute myocardial injury,kidney injury and liver injury caused by sepsis from the micro and ultra micro world,in order to provide some relevant theoretical basis for clinic.Methods: through the study of intravenous injection of E.coli endotoxin and bloodletting of experimental dogs to formed a "second blow",and tried to build a model dog of MODS caused by sepsis.The expression of matrix metalloproteinase-9(MMP-9)and tissue inhibitor of metalloproteinase-1(TIMP-1)m RNA and protein in left ventricular myocytes of dogs with heart failure which induced by sepsis were studied.After successful modeling,the changes of vital signs and related laboratory indexes of dogs were further monitored.At the same time,by studying the expression of miRNAs subtypes(miRNA-1,miRNA-133,miRNA-21,miRNA-29,miRNA-208,miRNA-499)in left ventricular myocytes of MODS model dogs with sepsis,this experiment further revealed whether MMP-9,TIMP-1 and miRNAs subtypes in ventricular myocytes of MODS model dogs with sepsis were involved in the occurrence of heart failure(HF).Whether there is the occurrence of septic cardiomyopathy(SC).Through the light and electron microscopic examination of the left ventricular muscle of the model dog,we further found the microstructure and super microstructure of the left ventricular muscle,kidney and liver when the heart failure occurred in the mods model dog caused by sepsis.Beagles of both sexes were selected and divided into two groups:control group and experimental group.Control group: healthy beagle dogs were treated with basic anesthesia and organ support without any treatment.Experimental group:healthy Beagle Dogs lost blood after intravenous injection of E.coli endotoxin after basic anesthesia,to form a "second blow",monitor the vital signs of beagle dogs and evaluate the change trend of laboratory related indicators with different time points.The methods used in this experiment were real-time quantitative polymerase chain reaction(real-time PCR)and Western blotting.The m RNA and protein expressions of MMP-9 and TIMP-1were measured by the above two methods;And the expression of miRNAs subtypes(miRNA-1,miRNA-133,miRNA-21,miRNA-29,miRNA-208,miRNA-499)was determined by real time PCR.The changes of microstructure and ultra microstructure of left ventricular muscle in two groups of model dogs were observed by light microscope and electron microscope.Results: the general vital signs of dogs in the experimental group were significantly worse than those in the control group.With different time points,the average arterial pressure of the experimental group was lower than that of the control group;The heart rate of the experimental group was higher than that of the control group;The body temperature of the experimental group was higher than that of the control group;The urine volume of the experimental group was lower than that of the control group;There was no significant difference in oxygen partial pressure.Laboratory related test indicators also changed with time.With different time points,homocysteine in the experimental group was higher than that in the control group;Creatinine and urea nitrogen in the experimental group were higher than those in the control group;Creatine kinase and creatine kinase isozymes in the experimental group were higher than those in the control group.Compared with the control group,the m RNA and protein expression levels of MMP-9 in canine left ventricular myocytes in the experimental group were up-regulated(P<0.05),and the m RNA and protein expression levels of tissue inhibitor TIMP-1 were up-regulated(P<0.05).Mi RNA-1,miRNA-133,miRNA-21,miRNA-29,miRNA-208 and miRNA-499 were expressed in canine left ventricular myocytes;The expression level of miRNA-21 in left ventricular muscle of dogs in the experimental group(2.21 ± 0.49)was significantly higher than that in the control group(P<0.05);However,although the other five subtypes(miRNA-1,miRNA-133,miRNA-29,miRNA-208 and miRNA-499)were expressed,there was no significant difference(P>0.05).The microstructure of the cells was observed by light and electron microscopic examination of the left ventricular muscle of the model dog.Under light microscope,the myocardial structure of dogs in the experimental group showed ischemia-hypoxia like injury,and the arrangement of myocardial cells was disordered.Under electron microscope: the arrangement order of myocardial cells in the experimental group was obviously irregular and disordered.Some myocardial cell bundles were broken and ZM bands were blurred;The mitochondrial mass density decreased and slightly deformed.And we are found some mitochondrial cristae were incomplete and mitochondrial edema and mitochondrial membrane damage.Which autophagy lysosomes were found and some mitochondria formed a small amount of vacuoles.The vacuolar mitochondria were scattered.Conclusion: the dog model of MODS caused by sepsis can be successfully established by intravenous injection of endotoxin and blood loss.After modeling,the vital signs of dogs were monitored.It was found that the vital signs of model dogs in the experimental group were significantly worse than those in the control group,and the laboratory indexes were also significantly worse.The up regulation of m RNA and protein expression of MMP-9 and inhibitor TIMP-1 and the up regulation of miRNA-21 may be involved in the occurrence of heart failure caused by sepsis.By observing the microstructure and ultra microstructure of dogs under light microscope and electron microscope,we found that acute ischemia-hypoxia like changes occurred in myocardium,kidney and liver of model dogs in the experimental group when heart failure caused by sepsis,especially in heart and kidney.And we also found an interesting phenomenon of mitochondrial autophagy and mitochondrial apoptosis through the ultra microstructure.