The endothelin system and its role in acute myocardial infarction

Metabolomics for Biomarker Discovery in Fermented Black Garlic and Potential Bioprotective Responses against Cardiovascular Diseases

Fermented black garlic has multiple beneficial biological activities, including cardiovascular protection, anticancer, hepatoprotective, and antibacterial properties. In this study, metabolic differences in the properties of black and fresh garlic were investigated via liquid chromatography quadrupole/time-of-flight-based metabolomics, leading to the identification of characteristic components. Fermented black garlic samples and their Amadori products (AC) promoted angiogenesis, prevented thrombus formation by rescuing chemical-induced vascular lesions in zebrafish, and inhibited H₂O₂-induced injury of endothelial cells, thus reducing the risk of cardiovascular disease. AC suppressed activation of the mitogen-activated protein kinase pathway through inhibition of p38 and ERK1/2 phosphorylation, in turn, increasing the availability of c-Fos/c-Jun or c-Jun/c-Jun complexes for apoptotic resistance. Clarification of the associated signaling pathways should therefore provide a solid foundation for optimization of black garlic-based therapies.

Receptor- and cellular compartment-specific activation of the cAMP/PKA pathway by α1-adrenergic and ETA endothelin receptors

The signalling functions of many G protein-coupled receptors (GPCRs) expressed in the myocardium are incompletely understood. Among these are the endothelin receptor (ETR) family and α₁-adrenergic receptor (α₁-AR), which are thought to couple to the G protein Gαq. In this study, we used transcriptome analysis to compare the signalling networks downstream of these receptors in primary neonatal rat cardiomyocytes. This analysis indicated increased expression of target genes of cAMP responsive element modulator (CREM) after 24 h treatment with the α₁-AR agonist phenylephrine, but not the ETR agonist endothelin-1, suggesting a specific role for the α₁-AR in promoting cAMP production in cardiomyocytes. To validate the difference observed between these two GPCRs, we used heterologous expression of the receptors and genetically encoded biosensors in HEK 293 cell lines. We validated that both α_1A- and α_1B-AR subtypes were able to lead to the accumulation of cAMP in response to phenylephrine in both the nucleus and cytoplasm in a Gαs-dependent manner. However, the ETR subtype ETA did not affect cAMP levels in either compartment. All three receptors were coupled to Gαq signalling as expected. Further, we showed that activation of PKA in different compartments was α₁-AR subtype specific, with α_1B-AR able to activate PKA in the cytoplasm and nucleus and α_1A-AR only able to in the nucleus. We provide evidence for a pathway downstream of the α₁-AR, and show that distinct pools of a receptor lead to differential activation of downstream effector proteins dependent on their cellular compartment.

HSP27 Inhibits Homocysteine-Induced Endothelial Apoptosis by Modulation of ROS Production and Mitochondrial Caspase-Dependent Apoptotic Pathway

Objectives. Elevated plasma homocysteine (Hcy) could lead to endothelial dysfunction and is viewed as an independent risk factor for atherosclerosis. Heat shock protein 27 (HSP27), a small heat shock protein, is reported to exert protective effect against atherosclerosis. This study aims to investigate the protective effect of HSP27 against Hcy-induced endothelial cell apoptosis in human umbilical vein endothelial cells (HUVECs) and to determine the underlying mechanisms. Methods. Apoptosis, reactive oxygen species (ROS), and mitochondrial membrane potential (MMP) of normal or HSP27-overexpressing HUVECs in the presence of Hcy were analyzed by flow cytometry. The mRNA and protein expression levels were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. Results. We found that Hcy could induce cell apoptosis with corresponding decrease of nitric oxide (NO) level, increase of endothelin-1 (ET-1), intracellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1 (VCAM-1), and monocyte chemoattractant protein-1 (MCP-1) levels, elevation of ROS, and dissipation of MMP. In addition, HSP27 could protect the cell against Hcy-induced apoptosis and inhibit the effect of Hcy on HUVECs. Furthermore, HSP27 could increase the ratio of Bcl-2/Bax and inhibit caspase-3 activity. Conclusions. Therefore, we concluded that HSP27 played a protective role against Hcy-induced endothelial apoptosis through modulation of ROS production and the mitochondrial caspase-dependent apoptotic pathway.

[Effects of salvianolic acid B on cardiovascular endothelial cells and platelet activation in a rabbit model of ischemia-reperfusion]

OBJECTIVE

To investigate the effects of salvianolic acid B (SA-B) on cardiovascular endothelial cell function and platelet activation during myocardial ischemia-reperfusion in rabbits.

METHODS

A total of 24 New Zealand white rabbits were randomly divided into sham-operated group, ischemia-reperfusion group (untreated group) and SA-B group. The hearts of rabbits in untreated group and SA-B group underwent half an hour of left anterior descending coronary artery (LADCA) occlusion via ligation technology, which was followed by 4 hours of reperfusion to prepared ischemia-reperfusion injury model in vivo. For sham-operated group, the animals were not subjected to occlusion of LADCA. In SA-B treatment group the rabbits were intravenously administered SA-B immediately after LADCA occlusion, and the other two groups were given normal saline in the same way instead of SA-B. The jugular vein bloods of animals were collected before LADCA ligation, half an hour after ligation and after 1-, 4-hour reperfusion, respectively. The content of plasma nitric oxide (NO) was determined by nitrate reductase process. Radioimmunoassay was applied to detect the endothelin (ET) content in plasma and the count of alpha-granule membrane protein-140 (GMP-140) on platelet surface to identify the activation of the platelet.

RESULTS

No significant difference was observed before and after sham LADCA occlusion in sham-operated group in the contents of NO and ET in plasma (P>0.05), neither was the count of GMP-140 on platelet surface (P>0.05). The content of NO in plasma detected 0.5 h after LADCA occlusion was significantly decreased in untreated group compared with the sham-operated group at the corresponding time, and they were also much lower than that before LADCA occlusion in the sham-operated group (P<0.05). The plasma content of NO in untreated group showed a progressive decrease in response to the myocardial reperfusion. However, the content of ET in plasma and the count of GMP-140 on platelet surface were remarkably increased after myocardial ischemia as compared with those before LADCA ligation and those detected in sham-operated group (P<0.05). The content of ET and the count of GMP-140 in the untreated group were further increased corresponding to the aggressive reperfusion. The content of NO was significantly increased while the content of ET and the count of GMP-140 were both significantly decreased in SA-B group as compared with untreated group after 1- and 4-hour myocardial reperfusion, respectively (P<0.01).

CONCLUSION

The results show that endothelial dysfunction and platelet activation occur during ischemia-reperfusion in rabbit hearts in vivo and SA-B protects cardiovascular endothelium cells against ischemia-reperfusion injury and inhibits the activation of platelet during myocardial ischemia and reperfusion.

Oral administration of geranylgeranylacetone blunts the endothelial dysfunction induced by ischemia and reperfusion in the rat heart

It has been shown that geranylgeranylacetone (GGA) protects heart against ischemia/reperfusion injury via enhanced heat shock protein 72 (HSP72) expression in rats. In the present study, we investigated the protective effect of GGA on ischemia/reperfusion-induced endothelial dysfunction. Rats were given oral GGA (GGA group) or vehicle (CON group), and 24 hours later their hearts were removed and placed in the Langendorff apparatus for 30-minute low-flow ischemia followed by 30-minute reperfusion. GGA improved the postischemic functional recovery (P < 0.01), which was abolished by N-nitro-L-arginine methyl ester (L-NAME, NO synthase inhibitor). NO production during both ischemia and reperfusion were increased in the GGA group, and the acetylcholine (ACh)-induced (endothelium-dependent) vasodilation, measured as the percentage decrease in coronary perfusion pressure after ischemia/reperfusion (14.9 +/- 1.3%), was preserved as compared with that in the CON group (7.9 +/- 1.4%). LY294002, a phosphatidylinositol 3 (PI3) kinase inhibitor, abolished the protective effects of GGA on endothelial-dependent coronary vasodilation and NO production, whereas Y27632 (Rho kinase inhibitor) increased endothelium-dependent coronary vasodilation and NO production in CON group toward the level seen in GGA group. The amount of adrenomedullin in the coronary effluent at basal condition was lower in the GGA group than in the CON group (P < 0.05), and during both ischemia and reperfusion there was no difference in the amount of adrenomedullin between the GGA and CON groups. In addition, no difference was observed in the amount of endothelin-1 between the GGA and CON groups. These results indicate that GGA attenuates the ischemia/reperfusion-induced coronary endothelial dysfunction, which may contribute to its cardioprotective effect. The PI3 kinase and/or Rho kinase pathways appear to be involved in this process, whereas adrenomedullin and endothelin-1 are not necessary for the GGA-induced cardioprotection.