| Background and objectsWith the development of society and people's lifestyle changes, diabetes (diabetes mellitus, DM) incidence trend of increasing year by year. Data show that diabetes risk was 3 times the non-diabetic population. In the insulin and antibiotic ago,diabetic ketoacidosis, and infections are the leading cause of death. With the improvement of health conditions, cardiovascular disease, kidney disease and other chronic complications of becoming the leading cause of death, including myocardial infarction (myocardial infarction, MI) is the serious type. According to the literature, DM patients with acute myocardial infarction (acute myocardial infarction, AMI) incidence rate in 2-3 times higher in patients with non-DM, DM patients is one of the major causes of death, so DM is associated with the MI study between the more and more attention. Myocardial infarction patients with diabetes with ventricular arrhythmias and sudden death than the risk of diabetes or myocardial infarction alone significantly increased. Many others as well as our previous study confirmed the existence of myocardial infarction cardiac autonomic nerve reconstruction, and ventricular arrhythmias after myocardial infarction and sudden death are closely related; and numerous studies confirm that diabetes itself, there are varying degrees of cardiac autonomic nerve damage, but on the basis of DM autonomic neuropathy occurred after MI changes in cardiac autonomic nerves, as well as the relevance of ventricular arrhythmias has been few reported.In recent years, there are many studies abuout myocardial infarction for the change of cardiac autonomic nerves,but mainly for the sympathetic. Many others as well as our Previous study found that after myocardial infarction sympathetic denervation to a large number from the proliferation of dynamic evolution, resulting in a more uneven distribution of sympathetic spatial distribution of the phenomenon in ventricular arrhythmia and cardiac sudden death to maintain an important role. But changes after myocardial infarction parasympathetic little research has been reported. Recently, studies have shown that changes in the parasympathetic after myocardial infarction have a major impact on sympathetic remodeling and electrical remodeling, but the reconstruction process after myocardial infarction and arrhythmia relationship need for further research.The main objects of this study are:1)Diabetic animal model with myocardial infarction were erected in rabbits, and immunohistochemistry and real time fluorescent quantitation reverse transcription polymerase chain reaction (RT-PCR) were used to observe the influences of diabetes on the cardiac parasympathetic nerve.2)we use the method programmed stimulation (programmed electrical stimulation, PES) induced ventricular arrhythmia and explore the relationship between the chang of parasympathetic nerve after DM with MI with ventricular arrhythmia.Methods65 New Zealand rabbits were randomly divided into four groups:sham operation group rabbits (Sham, n=15) were not ligated coronary artery after opening the pericardium; MI group rabbits (n=15) were ligated coronary artery after opening the pericardium as the model of MI; diabetes sham group rabbits (DM, n=15) had normal diet for 1 week then were injected alloxan from the ear venous 80mg/Kg weight and were raised for 8 weeks before opening the pericardium, no ligation; diabetes with myocardial infarction group rabbits (DM+MI, n= 20) were ligated coronary artery on the basis of the model of diabetes. After 8 weeks, programmed electrical stimulation was applied to induce ventricular arrhythmias for the New Zealand white rabbits of survival; then the animals were killed from the infarction, left ventricular free wall, interventricular septum and right ventricle.we observed the morphology, distribution and density of AChE-positive nerve. We used real-time quantitative RT-PCR to observe the chang of AChE mRNA expression.ResultsOne of the DM group rabbits did not catch the standard of diabetes,two died of severe high glucoses and Complications, and finally 10 rabbits were accepted as diabetic rabbits and survived to end of the experiment., three of the MI group rabbits died; five of the DM+MI group rabbits died.Programmed electrical stimulation:The incidence of inducible ventricular arrhythmias in the Sham, DM, MI and DM with MI were 13.3%,50.0%*,66.7%# and 80.0%#§, respectively (*P<0.05 vs. Sham,#P<0.01 vs. Sham,§P<0.05 vs. DM).Immunohistochemical study found that AChE-positive nerve fibers:Sham group were mainly in the perivascular, and accompanied with vascular line and myocardial bundles were also distributed among the connective tissue; DM group:the distribution of AChE-positive nerve fibers were similar with the Sham group, but the density of nerve fibers were lower than the corresponding parts of Sham group (P<0.01); MI group:the spatial distribution of AChE-positive nerve fibers were disorders, in the small blood vessels around the connective tissue between bundles, as well as myocardial infarction and survival myocardial infarction overlapping weeks were distributed, some nerve fibers thick, the density higher than the Sham group (P<0.01); DM+MI group:the spatial distribution of nerve were disordered, the density higher than diabetes group (P<0.05).Real-time RT-PCR:Compared with the Sham group, the expression level of AChE mRNA decreased in the DM group and increased significantly the MI group (P<0.05), at the infarct border and the left ventricular free wall. In the DM with MI group, the expression of AChE mRNA was higher than that of the DM group (P<0.05).Conclusion1 MI can cause parasympathetic recovery remodeling.2 DM can cause varying degrees of cardiac parasympathetic damage. 3 DM with MI appeare cardiac parasympathetic reconstruction on the basis of neurological damage.
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