Sympathetic and metabolic changes induced by hyperglycemia in myocardial infarction

Abstract

This study was designed to evaluate the beneficial effects of hyperglycemic metabolism after myocardial infarction as well as changes in sympathetic marker.Male Wistar rats were divided into control (C), diabetic (D), myocardial infarction (MI) and diabetic myocardial infarction (DMI). Left coronary artery occlusion was performed after 15 or 30 days of diabetes (STZ) an accompanied by 2 or 15 days, respectively. The ventricular function, glycerol and norepinephrine levels were evaluated by echocardiography, biochemical kit and HPLC, respectively. The lipolysis was assessed by enzymes extracted from periepididymal adipose tissue. The area of infarction was 36% lower in DMI vs MI and the ejection (DMI: 82 ± 3 vs MI: 55 ± 3%) and shortening fraction (DMI: 48 ± 2 vs MI: 25 ± 2%) were preserved in DMI in comparison with MI. The glycerol was kept in 2 (2261 ± 180 mg/dl) and 15 (2756 ± 402 mg/dl) days after coronary occlusion in DMI, with 70% and 20% reduction in the weight of the adipose and adipocyte diameter as compared with D. The glycerol was decreased in MI after 2 (6245 ± 998) vs 15 (4355.45 ± 341mg/dl) days of MI vs C (7166 ± 1001mg/dl). Moreover, norepinephrine levels were decreased the MI group (5 ± 0.5 pg/ml) compared to the DMI (13 ± 1pg/ml). The results suggest an enhanced lipolysis in the MI group. Furthermore, diabetic animals had reduced infarcted area and improved ventricular function. These findings may be related to the increase in norepinephrine levels at the heart and the maintenance of lipolysis in this group, keeping thermogenesis in similar state as compared to normoglycemic animals.