Temporal and spatial expression of hypoxia-inducible factor-1alpha and vascular endothelial growth factor in a rat model of myocardial ischemia with or without reperfusion.
ABSTRACT Although hypoxia-inducible factor-1alpha (HIF-1alpha) plays a major role in the prevention of myocardial ischemia, the temporal and spatial patterns of expression of HIF-1alpha in myocardial ischemia-reperfusion are not well known. This study examined the role of HIF-1alpha and vascular endothelial growth factor (VEGF) in myocardial ischemia-reperfusion.
Adult Wistar rats were studied after ligation of the left anterior descending coronary artery (LAD) for 30 min and then after reperfusion. HIF-1alpha and VEGF were measured immediately after relief of occlusion and at 30 min, 1, 3, 6, and 24 h after reperfusion. HIF-1alpha and VEGF proteins were also measured 6 h after permanent occlusion of the LAD.
HIF-1alpha and VEGF mRNA increased 1.8- and 1.4-fold, respectively, immediately after relief of occlusion and reached a maximum of 4.3- and 2.3-fold, respectively, at 3 h after reperfusion and remained elevated up to 24 h. HIF-1alpha and VEGF proteins increased immediately after relief of ischemia. HIF-1alpha protein significantly increased from 0.5 h to 24 h after reperfusion and VEGF protein significantly increased from 1 h to 6 h after reperfusion compared to the sham control. Administration of HIF-1alpha antisense oligonucleotide before ligation of the LAD significantly inhibited VEGF protein expression induced by ischemia-reperfusion. Immunohistochemical study showed increased immunoreactivity of HIF-1alpha and VEGF in the jeopardized myocardium after ischemia-reperfusion. HIF-1alpha and VEGF proteins were increased at 6 h after permanent occlusion of the LAD.
This study demonstrated that HIF-1alpha and VEGF were co-induced in a temporal and spatial pattern after ischemia-reperfusion in the rat ventricular myocardium.
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ABSTRACT: Mechanical stress increases myocardial myostatin expression. However, the expression of myostatin in chronic heart failure resulting from volume-overload and after treatment with beta-blockers is little known. The authors hypothesize that myostatin plays a role in the failing myocardium because of volume-overload. Aorto-caval shunt was created over a 4-week period in adult Sprague-Dawley rats to induce volume-overload heart failure. Heart weight and body weight ratio significantly increased after shunting. The left ventricular end-diastolic dimension also significantly increased. Treatment with carvedilol in the shunt group reversed the increase in heart weight and ventricular dimension to the baseline values. Myocardial and skeletal myostatin proteins were up-regulated in the shunt group. The mRNA of myocardial myostatin also increased in the shunt group. Treatment with carvedilol reversed both protein and mRNA of myocardial myostatin to the baseline values. Treatment with N-acetylcysteine and doxazosin partially decreased myostatin mRNA and protein expression as compared with the shunt group. Carvedilol normalized the increased immunohistochemical labelling of myocardial myostatin in the shunt group. Myocardial myostatin mRNA and protein expression were up-regulated in the rat model of volume-overload heart failure. Treatment with carvedilol is associated with a limitation of increased myostatin expression in the failing ventricular myocardium.European Journal of Clinical Investigation 11/2006; 36(10):713-9. DOI:10.1111/j.1365-2362.2006.01718.x · 2.83 Impact Factor
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ABSTRACT: The present study investigated the immunohistochemical distributions and mRNA expressions of myocardial hypoxia-inducible factor (HIF)-1 alpha and its downstream factors, erythropoietin (Epo) and vascular endothelial growth factor (VEGF), in cardiac deaths. Medico-legal autopsy cases (n=114, within 48-h postmortem) of cardiac deaths (n=58) and control cases (n=56) were examined. Immunohistochemical positivities of HIF-1 alpha, Epo and VEGF were patchily observed in cardiomyocytes in the acute ischemic lesions of myocardial infarction (n=37), showing a relationship to morphological cardiomyocyte damage: the staining was intense in the regions with early ischemic changes and weak in the necrotic regions. Immunopositivities were sporadically detected in cardiomyocytes in some cases of sudden cardiac death without infarction (SCD, n=13). In chronic congestive heart disease (CHD, n=8), weak positivities were diffusely observed in the cardiomyocytes. However, there were no such findings in cases of mechanical asphyxiation (n=16) or drowning (n=18). HIF-1 alpha, Epo and VEGF mRNA expressions, as measured by real-time reverse transcription-polymerase chain reaction (RT-PCR), showed localized elevations related to acute myocardial infarction (AMI) lesions, whereas such findings were mild in recurrent myocardial infarction (RMI) and SCD cases. CHD showed significant elevations of these mRNAs irrespective of the sampling site. The mRNA expressions were significantly lower in cases of drowning. These findings suggest that focal immunopositivities and increased mRNAs of these factors are indicative of short and substantial duration of myocardial ischemia, respectively. The combined analyses may not only be useful for investigating the site, phase and severity of acute myocardial ischemia and the severity of chronic ischemic stress, but also contribute to differentiating cardiac deaths from asphyxiation and drowning or interpreting the possible contribution of cardiac disease in traumatic death.Legal Medicine 02/2008; 10(1):11-9. DOI:10.1016/j.legalmed.2007.06.002 · 1.44 Impact Factor
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ABSTRACT: Hypoxia-inducible factor (HIF) is the principal transcription factor involved in the regulation of transcriptional responses to hypoxia. During hypoxia, HIF-alpha levels accumulate and trigger an increase in expression of genes involved in glycolysis, glucose metabolism, mitochondrial function, cell survival, apoptosis, and resistance to oxidative stress. In this regard, HIF activation plays an essential role in triggering cellular protection and metabolic alterations from the consequences of oxygen deprivation. This suggests that HIF activation should confer protection against ischemia-reperfusion (I/R) injury, although this protection might require HIF activation before the onset of lethal ischemia. Studies using enhanced expression of HIF-1alpha suggest that its upregulation may be a beneficial therapeutic modality in the treatment or prevention of ischemic injury. HIF-regulated gene expression may mediate the late phase of preconditioning, and constitutive HIF activity may influence the expression of genes that are required for the cell to be able to respond to acute preconditioning. This article reviews the current literature on the role of HIF in balancing protection and cell death in the face of ischemia and I/R injury.Cell Death and Differentiation 05/2008; 15(4):686-90. DOI:10.1038/cdd.2008.13 · 8.39 Impact Factor