The use of beta-blockers has emerged as a beneficial treatment for cardiac hypertrophy. Hypoxia-inducible factor-1alpha (HIF-1alpha) is tightly regulated in the ventricular myocardium. However, the expression of HIF-1alpha in cardiac hypertrophy due to pressure overload and after treatment with beta-blocker is little known. To evaluate the effect of carvedilol on both myocardial HIF-1alpha expression and cardiac hypertrophy, infra-renal aortic banding was performed for 4 weeks in adult Sprague-Dawley rats to induce cardiac hypertrophy. Carvedilol at 50 mg/kg body weight per day after surgery was given. Heart weight and the ratio of heart weight and body weight increased significantly after aortic banding for 4 weeks in the absence of drug treatment. Mean arterial pressure increased from 80 +/- 9 mmHg in the sham group to 94 +/-5 mmHg (p < 0.001) in the banding group. Echocardiography showed concentric hypertrophy after aortic banding. Mean arterial pressure decreased after treatment with carvedilol. The increased wall thickness and heart weight was reversed to normal by carvedilol. Western blot showed that HIF-1alpha, vascular endothelial growth factor (VEGF) and brain natriuretic peptide (BNP) proteins were up-regulated and nerve growth factor-beta (NGF-beta) down-regulated in the banding group. Treatment with valsartan, doxazosin, or N-acetylcysteine did not significantly affect HIF-1alpha and VEGF proteins expression in the banding groups. Real-time polymerase chain reaction showed that mRNA of HIF-1alpha, VEGF and BNP increased and mRNA of NGF-beta decreased in the banding group. Treatment with carvedilol reversed both protein and mRNA of HIF-1alpha, VEGF, BNP, and NGF-beta to the baseline values. Increased immunohistochemical labeling of HIF-1alpha, VEGF, and BNP in the ventricular myocardium was observed in the banding group and carvedilol again normalized the labeling. In conclusion, HIF-1alpha, VEGF, and BNP mRNA and protein expression were up-regulated, while NGF-beta mRNA and protein was downregulated in the rat model of pressure-overloaded cardiac hypertrophy. Treatment with carvedilol is associated with a reversal of abnormal regulation of HIF-1alpha, VEGF, BNP, and NGF-beta in the hypertrophic myocardium.

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Endothelin-1 (ET-1) has been found to increase cardiac beta-myosin heavy chain (beta-MyHC) gene expression and induce hypertrophy in cardiomyocytes. ET-1 has been demonstrated to increase intracellular reactive oxygen species (ROS) in cardiomyocytes. The exact molecular mechanism by which ROS regulate ET-1-induced beta-MyHC gene expression and hypertrophy in cardiomyocytes, however, has not yet been fully described. We aim to elucidate the molecular regulatory mechanism of ROS on ET-1-induced beta-MyHC gene expression and hypertrophic signaling in neonatal rat cardiomyocytes. Following stimulation with ET-1, cultured neonatal rat cardiomyocytes were examined for 3H-leucine incorporation and beta-MyHC promoter activities. The effects of antioxidant pretreatment on ET-1-induced cardiac hypertrophy and mitogen-activated protein kinase (MAPKs) phosphorylation were studied to elucidate the redox-sensitive pathway in cardiomyocyte hypertrophy and beta-MyHC gene expression. ET-1 increased 3H-leucine incorporation and beta-MyHC promoter activities, which were blocked by the specific ET(A) receptor antagonist BQ-485. Antioxidants significantly reduced ET-1-induced 3H-leucine incorporation, beta-MyHC gene promoter activities and MAPK (extracellular signal-regulated kinase, p38, and c-Jun NH2 -terminal kinase) phosphorylation. Both PD98059 and SB203580 inhibited ET-1-increased 3H-leucine incorporation and beta-MyHC promoter activities. Co-transfection of the dominant negative mutant of Ras, Raf, and MEK1 decreased the ET-1-induced beta-MyHC promoter activities, suggesting that the Ras-Raf-MAPK pathway is required for ET-1 action. Truncation analysis of the beta-MyHC gene promoter showed that the activator protein-2 (AP-2)/specificity protein-1 (SP-1) binding site(s) were(was) important cis-element(s) in ET-1-induced beta-MyHC gene expression. Moreover, ET-1-induced AP-2 and SP-1 binding activities were also inhibited by antioxidant. These data demonstrate the involvement of ROS in ET-1-induced hypertrophic responses and beta-MyHC expression. ROS mediate ET-1-induced activation of MAPK pathways, which culminates in hypertrophic responses and beta-MyHC expression.

Background/Aims: Nicorandil, an ATP-sensitive potassium (K_ATP) channel opener, nitric oxide (NO) donor and antioxidant, was shown to exert a variety of pharmacological effects including cardioprotective properties. However, its mechanisms of action are not completely understood. The aims of this study were to examine whether nicorandil may alter angiotensin-II (Ang II)-induced cell proliferation and to identify the putative underlying signaling pathways in rat cardiac fibroblasts. Methods: Cultured rat cardiac fibroblasts were pretreated with nicorandil, then stimulated with Ang II, and cell proliferation and endothelin-1 (ET-1) expression were examined. The effects of nicorandil on Ang-II-induced reactive oxygen species (ROS) formation and extracellular signal-regulated kinase (ERK) phosphorylation were also examined. In addition, the effects of nicorandil on NO production and endothelial nitric oxide synthase (eNOS) phosphorylation were tested to elucidate the intracellular mechanism. Results: Nicorandil (0.1–10 µmol/l) caused a concentration-dependent inhibition of Ang-II-increased cell proliferation and ET-1 expression which were prevented by the K_ATP channel blocker glibenclamide (1 µmol/l). Nicorandil also inhibited Ang-II-increased ROS and ERK phosphorylation. In addition, nicorandil was found to increase the NO and eNOS phosphorylation. N-nitro-L-arginine methyl ester, an inhibitor of NOS, and the short interfering RNA transfection for eNOS markedly attenuated the inhibitory effect of nicorandil on Ang-II-induced cell proliferation. Conclusion: Our results suggest that nicorandil prevents cardiac fibroblast proliferation, and the inhibitory effect might be associated with the opening K_ATP channels, by interfering with the generation of ROS, and the activation of the eNOS-NO pathway.

Background Gastrointestinal bleeding is a hemorrhagic complication after primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction (STEMI). Objectives To determine predictors of gastrointestinal bleeding and the impact of gastrointestinal bleeding on outcomes in STEMI patients undergoing primary percutaneous coronary intervention. Methods and ResultsGastrointestinal bleeding occurred in 18 (3.5%) of 519 consecutive patients with STEMI undergoing primary percutaneous coronary intervention. Univariate predictors of gastrointestinal bleeding were previous gastrointestinal bleeding (33% vs 4%, P < .001), impaired renal function (89% vs 37%, P < .001), Killip class IV at presentation (61% vs 18%, P < .001), higher peak creatinine kinase level (mean [SD], 3801.6 [3280.2] vs 2721.3 [2286.6] IU/L, P = .05), and mechanical ventilator support (44% vs 12%, P < .001). Co pre scription of proton-pump inhibitors did not reduce the risk of gas tro in tes ti nal bleeding (22.2% vs 13.4%, P = .22). Multivariate analysis showed an odds ratio (95% confidence interval) for gastrointestinal bleeding of 22.1 (5.6-86.89, P < .001) for previous gastrointestinal bleeding, 6.74 (1.30-34.89, P = .02) for impaired renal function, and 4.68 (1.35-16.2, P = .01) for Killip class IV at pres en tation. Gastrointestinal bleeding was associated with longer inten sive care unit stay (mean [SD], 5.4 [6.7] vs 3.6 [3.6] days, P = .04), and higher in-hospital (44% vs 9%, P < .001) and overall (44% vs 13%, P < .001) mortality rate. Conclusions Although rare, gastrointestinal bleeding in patients with STEMI significantly prolongs intensive care unit stay and increases mortality. Previous gastrointestinal bleeding, impaired renal function, and Killip class IV at presentation are associated with higher incidence of gastrointestinal bleeding.