Author + information
Acute myocardial infarction (AMI) is one of the most serious diseases that threaten human's health. It indicates that there are 114 million diabetics and 148.2 million prediabetics in China. China has become a diabetes capital all over the world. About 65 percent of people with diabetes die from heart disease. Strong evidence exists that diabetics suffer from increased incidence and severity of myocardial infarction (MI) and are much more likely to suffer from heart failure following MI. It is still controversial about the sensitivity of myocardium for the MI injury in diabetic. It is not verified that diabetic duration maybe a factor in the sensitivity of myocardium for the MI injury in diabetic. The aim of this study was to investigate the effects of diabetic duration on left ventricular dysfunction and heart failure after AMI and its mechenism.
The non-diabetic (group1, n=20) and age-matched non-diabetic (group2, n=50) mice were subjected to myocardial infarction at 1 day (n=10), 7 days (n=10), 14 days (n=10), 30 days (n=10) after the establishment of diabetes, respectively. Mouse were rendered diabetic by 5 days of daily intraperitoneal injection with 40mg/kg STZ (Sigma) in 0. 05 M sodium citrate, pH 4.5. Blood glucose was measured 2 days after the final injection, and diabetic condition was confirmed by markedly elevated fasting -blood glucose levels (>11.1umol/L). Mouse underwent myocardial infarction by ligating the left anterior descending coronary artery with injection of saline. Sham-operated mouse underwent the same surgical procedures except that the suture placed under the left anterior descending coronary artery was not ligated. Myocardial tissue sections were traced and stained with immunofluorescence to find cells which glowing red fluorescent and alpha sarcomeric actin positive under fluorescence microscope. Cardiac functionwas monitored using echocardiography after 4 weeks in half mouse of every subgroup.
The fasting-blood glucose level was elevated with diabetic duration increasing. Compare with the control group 1, there were lower left ventricular ejection fraction (p＜0.001), longer fraction (p＜0.001) and larger left ventricular end-diastolic volume (p＜0.001) in the experimental group 2. In addition, there were lowest left ventricular ejection fraction, longest fraction and largest left ventricular end-diastolic volume in the 30-day diabetic mouse sub-group of group 2. Diabetic duration may decrease the sensitivity of myocardium for the MI injury in diabetic mice.
The MI injury is time-dependently increased in diabetic mice. The longer diabetes duration mice may have less sensitivity for MI injury.