Hyperglycaemia protects the heart after myocardial infarction: aspects of programmed cell survival and cell death

• Published in: European journal of heart failure Vol. 12; no. 7; pp. 659 - 667
• Main Authors: Malfitano, Christiane, Alba Loureiro, Tatiana C., Rodrigues, Bruno, Sirvente, Raquel, Salemi, Vera Maria Cury, Rabechi, Nara B., Lacchini, Silvia, Curi, Rui, Irigoyen, Maria Claudia C.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-07-2010
• Subjects: Angiogenesis; Animals; Apoptosis; Apoptosis - physiology; Caspase 3 - metabolism; Cell Survival - physiology; Cytokines - analysis; Diabetes Mellitus, Experimental - physiopathology; Diabetic hyperglycaemia; Fibrosis; Glucose Transport Proteins, Facilitative - metabolism; Heart - physiopathology; Hyperglycemia - physiopathology; Inflammation; Male; Myocardial infarction; Myocardial Infarction - physiopathology; Myocytes, Cardiac - physiology; Rats; Tumor Necrosis Factor-alpha - metabolism; Vascular Endothelial Growth Factor A - metabolism
• ISSN: 1388-9842; 1879-0844
• DOI: 10.1093/eurjhf/hfq053

Aims
Exposure to a high glucose medium or diabetes has been found to protect the heart against ischaemia. The activation of antiapoptotic and proliferative factors seems to be involved in this cardioprotection. This study was designed to evaluate the role of hyperglycaemia in cardiac function, programmed cell survival, and cell death in diabetic rats after myocardial infarction (MI).
Methods and results
Male Wistar rats were divided into four groups (n = 8): control (C), diabetic (D), myocardial infarcted (MI), and diabetic myocardial infarcted (DI). The following measures were assessed in the left ventricle: size of MI, systolic and diastolic function by echocardiography, cytokines by ELISA (TNF‐α, IL‐1β, IL‐6, and IL‐10), gene expression by real‐time PCR (Bax, Fas, p53, Bcl‐2, HIF1‐α, VEGF, and IL8r), caspase‐3 activity by spectrofluorometric assay, glucose transporter type 1 and 4 (GLUT‐1 and GLUT‐4) protein expression by western blotting, and capillary density and fibrosis by histological analysis. Systolic function was improved by hyperglycaemia in the DI group, and this was accompanied by no improvement in diastolic dysfunction, a reduction of 36% in MI size, reduced proinflammatory cytokines, apoptosis activation, and an increase in cell survival factors (HIF1‐α, VEGFa and IL8r) assessed 15 days post‐MI. Moreover, hyperglycaemia resulted in angiogenesis (increased capillary density) before and after MI, accompanied by a reduction in fibrosis.
Conclusion
Together, these results suggest that greater plasticity and cellular resistance to ischaemic injury result from chronic diabetic hyperglycaemia in rat hearts.