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: l-Tetrahydropalmatine (l-THP) is an active ingredients of Corydalis yanhusuo W.T. Wang, which protects against acute global cerebral ischaemia-reperfusion injury. In this study, we show that l-THP is cardioprotective in myocardial ischaemia-reperfusion injury and examined the mechanism. Rats were treated with l-THP (0, 10, 20, 40 mg/kg b.w.) for 20 min before occlusion of the left anterior descending coronary artery and subjected to myocardial ischaemia-reperfusion (30 min/6 h). Compared with vehicle-treated animals, the infarct area/risk area (IA/RA) of l-THP (20, 40 mg/kg b.w.) treated rats was reduced, whilst l-THP (10 mg/kg b.w.) had no significant effect. Cardiac function was improved in l-THP-treated rats whilst plasma creatine kinase activity declined. Following treatment with l-THP (20 mg/kg b.w.), subunit of phosphatidylinositol 3-kinase p85, serine(473) phosphorylation of Akt and serine(1177) phosphorylation of endothelial NO synthase (eNOS) increased in myocardium, whilst expression of inducible NO synthase (iNOS) decreased. However, the expression of HIF-1α and VEGF were increased in I(30 min)R(6 h), but decreased to normal level in I(30 min)R(24 h), while treatment with l-THP (20 mg/kg b.w.) enhanced the levels of these two genes in I(30 min)R(24 h). Production of NO in myocardium and plasma, activity of myeloperoxidase (MPO) in plasma and the expression of tumour necrosis factor-α (TNF-α) in myocardium were decreased by l-THP. TUNEL assay revealed that l-THP (20 mg/kg b.w.) reduced apoptosis in myocardium. Thus, we show that l-THP activates the PI3K/Akt/eNOS/NO pathway and increases expression of HIF-1α and VEGF, whilst depressing iNOS-derived NO production in myocardium. This effect may decrease the accumulation of inflammatory factors, including TNF-α and MPO, and lessen the extent of apoptosis, therefore contributing to the cardioprotective effects of l-THP in myocardial ischaemia-reperfusion injury.PLoS ONE 06/2012; 7(6):e38627. · 3.53 Impact Factor
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ABSTRACT: Recent studies have shown that the polyol pathway is involved in ischemia–reperfusion (I/R)-induced myocardial infarction, but the mechanism is unclear. We previously found that lack of aldose reductase (AR), the first enzyme of the polyol pathway, attenuated the increase in transferrin (Tf) level in I/R brain, suggesting that AR contributes to iron-catalyzed free radical-induced damage. We therefore investigated if this mechanism occurs in I/R hearts. We found that inhibition of AR or sorbitol dehydrogenase (SDH), the second enzyme of the polyol pathway, both attenuated the I/R-mediated increases in HIF-1α, Tf, TfR, and intracellular iron content and reduced the I/R-induced infarct area of the heart. Further, administration of niacin, which replenishes NAD+, the cofactor for SDH, also normalized TfR and HIF-1α levels in I/R hearts. These results suggest that during I/R polyol pathway activity increases the cytosolic NADH/NAD+ ratio. This activates HIF-1α that induces the expression of TfR, which in turn increases Tf uptake and iron accumulation and exacerbates oxidative damage that increases the lipid peroxidation. This was confirmed by the fact that administration of the iron chelator deferoxamine attenuated the I/R-induced myocardial infarction.Free Radical Biology and Medicine 09/2008; · 5.71 Impact Factor
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ABSTRACT: Changes in cardiac gene expression due to myocardial injury are usually assessed in whole heart tissue. However, as the heart is a heterogeneous system, spatial and temporal heterogeneity is expected in gene expression. In an ischemia/reperfusion (I/R) rat model we evaluated gene expression of mitochondrial and cytoplasmatic superoxide dismutase (MnSod, Cu-ZnSod) and thioredoxin reductase (trxr1) upon short (4 h) and long (72 h) reperfusion times in the right ventricle (RV), and in the ischemic/reperfused (IRR) and the remote region (RR) of the left ventricle. Gene expression was assessed by Real-time reverse-transcription quantitative PCR (RT-qPCR). In order to select most stable reference genes suitable for normalization purposes, in each myocardial region we tested nine putative reference genes by geNorm analysis. The genes investigated were: Actin beta (actb), Glyceraldehyde-3-P-dehydrogenase (gapdh), Ribosomal protein L13A (rpl13a), Tyrosine 3-monooxygenase (ywhaz), Beta-glucuronidase (gusb), Hypoxanthine guanine Phosphoribosyltransferase 1 (hprt), TATA binding box protein (tbp), Hydroxymethylbilane synthase (hmbs), Polyadenylate-binding protein 1 (papbn1). According to our findings, most stable reference genes in the RV and RR were hmbs/hprt and hmbs/tbp/hprt respectively. In the IRR, six reference genes were recommended for normalization purposes; however, in view of experimental feasibility limitations, target gene expression could be normalized against the three most stable reference genes (ywhaz/pabp/hmbs) without loss of sensitivity. In all cases MnSod and Cu-ZnSod expression decreased upon long reperfusion, the former in all myocardial regions and the latter in IRR alone. trxr1 expression did not vary. This study provides a validation of reference genes in the RV and in the anterior and posterior wall of the LV of cardiac ischemia/reperfusion model and shows that gene expression should be assessed separately in each region.BMC Research Notes 02/2012; 5:124.