| Background:Diabetic patients with coronary heart disease have a mortality accounts for almost 50%,which is 2 to 4 times compare with the non-diabetic patients.In the surviving population of acute myocardial infarction, 50% still died of fatal ventricular arrhythmia.Ventricular remodeling after myocardial infarction is the main factor which leads to ventricular arrhythmias.Experiments showed that after myocardial infarction cardiac hupertrophy,proliferation differentiation and apoptosis toke part in ventricular remodeling in the surrounding region,and diabetes (diabetes mellitus, DM) also had effect on the heart cells.This study compared the changes of cardiac hupertrophy,proliferation differentiation and apoptosis in type 2 diabetic rats after myocardial infarction in non-infarcted areas,to explore the effect of type 2 diabetes mellitus (T2DM) on left ventricular remodeling after myocardial infarction. Objective:To explore the effect of diabetes on the ventricular remodeling in non-infarcted areas after myocardial infarction in type 2 diabetic rats by comparing the changes of cardiac hypertrophy,proliferation differentiation and apoptosis.Methods:1, experimental materials, 50 male SD rats, weighing 180 ~ 220g, from the Fourth Military Medical University Experimental Animal Center. Roche main instrument has blood glucose meter, multi-channel physiological recorder, optical microscopy, computer image analysis system. Main reagents are alloxan (ALX, Sigma Company), rabbit anti-mouse transforming growth factor-β1 (TGF-β1) antibody (Boster Company), mouse anti-rat proliferating cell nuclear antigen (PCNA) (Boster Company), to-use SABC kit (Boster Company), in situ apoptosis kit (Boster Company), DAB color kit (Boster Company). 2, DM+MI model and the experimental group (1) T2DM rat model of reference method produced such reports Guirong T2DM rats, that is, improved fat emulsion (20 g refined lard, 1 g C S PTU, 10 g cholesterol, 1 g sodium glutamate, 5 g sugar, 5 g fructose, 20 ml Tween -80,3 0ml propylene glycol water will dissolve to 100 ml) orally, has been fed the standard diet during the period. After 10 d, fasting, but still fed water, after the night,weighing, according to two administration methods intraperitoneally ALX, 1st intraperitoneal injection of 3% ALX solution (in the ice bath before use under the conditions of freshly prepared with saline), 2nd intraperitoneal injection of 2.5% ALX solution (ibid.), the first two days and then repeated the treatment. Blood glucose was measured by Roche after the last administration 72 h of fasting blood glucose (FBG), FBG≥11.1 mmol / L were determined for the T2DM rats. (2) MI rat model of reference Himori other methods reported, that 10 g / L sodium pentobarbital by 46 mg / kg intraperitoneal dose of anesthetized rats. Thoracotomy exposed the heart, the left atrial appendage and the pulmonary cone around the left main coronary artery between the marked Department through the 5 / 0 silk thread, ECG showed off layer after successful coronary artery ligation chest; the control group without coronary artery ligation after threading. (3) animals in group 50 rats, 32 survived. Normal control group, DM group (only induced DM), MI control group (only induced MI) and DM + MI group (established T2DM rat MI model) of the eight in each group continue to use the standard diet for 4 weeks after the drawn Detection and analysis. 3 Immunohistochemical staining with TGF-β1 and PCNA expression. 4, using TUNEL assay apoptosis of myocardial cells. 5, image analysis: TGF-β1 using the Image-pro plus6.0 software and special microscope images for quantitative analysis of protein through the positive area ratio in the constituency that each slide in the 40×objective lens under test, then View 10 selected to calculate the average; PCNA expression and apoptosis is the Olympus micrometer eyepiece grid placed within the microscope at low magnification to find the lesion after the high-power microscope (×4OO) under the random selection of 10 independent view, select the View 100 for each cell, the statistics of the number of positive cells, the cells of 10 View add as 1 O00 a myocardial cells the number of positive cells to calculate the percentage of positive cells. 6, statistical results that are±s. Statistical analysis using SPSS 15.0 software was used to compare results between groups analysis of variance, with P≤0.05 statistically significant differences were indicated. Results:1, TGF-β1 expression of immunohistochemical staining results showed, DM controls the expression of TGF-β1 compared with normal control group was significantly higher (P <0.01). In DM + MI group,the expression of TGF-β1 surrounding infarct area was significantly higher compared the MI control group, DM group and control group(P <0.01). 2,The expression of PCNA was similar expression of TGF-β1, DM control group was significantly higher than the normal control group,In DM + MI group,the expression of PCNA surrounding infarct area was significantly higher compared the MI control group, DM group and control group(P <0.01), and mostly occur in sheets together. 3,TUNEL assay showed,in DM control group the number of apoptotic cells increased significantly compared with normal control group, and the MI control group,in DM + MI group the number of apoptotic cells around the infarct area was significantly higher compared the MI control group, DM group and control group.Conclusion:DM upregulated the renin-angiotensin system(RAAS)'s activity, AngⅡis an important conditioning factor of RAAS, we suggests that the significantly increased expression of TGF-β1 in DM + MI group compared with DM and MI group was due to the existence basis disease of DM myocardial cells, AngⅡ's inotropic action and vasoconstriction after myocardial infarction increased myocardial oxygen consumption and reduced myocardial blood supply which increased myocardial ischemic damage, so that further enhanced RAAS's activity, AngⅡ's upregulation of expression and activity created a vicious cycle,which stimulate TGFβ1 synthesis. There was a certain degree of diabetes microvascular disease, RAAS's activity increased after myocardial infarction,which induced vasoconstriction and positive inotropic effect expanded the scope of myocardial ischemia,may be the reason of the greatly improving of PCNA's expression in DM+ MI group. DM can make normal heart cells apoptosis, in MI, it can increase ischemic damage of heart cells, thus promoting apoptosis of myocardial cells.In summary, in a case of DM,there is a degree of hypertrophy, proliferation and apoptosis in myocardial cells, particularly apoptosis positive rate is much higher than the MI control group, suggesting that the heart of the DM rats is extremely sensitive to ischemic injury,and there is such a degree of cardiac microangiopathy. in DM complicated MI, the process of ventricular remodeling obvious cardiac hypertrophy, proliferation and apoptosis, and were significantly higher than the DM control group and the MI control group, may be the pathophysiological basis of the high arrhythmias and the high mortality rate after myocardial infarction.
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