Coronary collateralization shows sex and racial-ethnic differences in obstructive artery disease patients.

BACKGROUND: Coronary collateral circulation protects cardiac tissues from myocardial infarction damage and decreases sudden cardiac death. So far, it is unclear how coronary collateralization varies by race-ethnicity groups and by sex. METHODS: We assessed 868 patients with obstructive CAD. Patients were assessed for collateral grades based on Rentrop grading system, as well as other covariates. DNA samples were genotyped using the Affymetrix 6.0 genotyping array. To evaluate genetic contributions to collaterals, we performed admixture mapping using logistic regression with estimated local and global ancestry. RESULTS: Overall, 53% of participants had collaterals. We found difference between sex and racial-ethnic groups. Men had higher rates of collaterals than women (P-value = 0.000175). White Hispanics/Latinos showed overall higher rates of collaterals than African Americans and non-Hispanic Whites (59%, 50% and 48%, respectively, P-value = 0.017), and especially higher rates in grade 1 and grade 3 collateralization than the other two populations (P-value = 0.0257). Admixture mapping showed Native American ancestry was associated with the presence of collaterals at a region on chromosome 17 (chr17:35,243,142-41,251,931, ß = 0.55, P-value = 0.000127). African ancestry also showed association with collaterals at a different region on chromosome 17 (chr17: 32,266,966-34,463,323, ß = 0.38, P-value = 0.00072). CONCLUSIONS: In our study, collateralization showed sex and racial-ethnic differences in obstructive CAD patients. We identified two regions on chromosome 17 that were likely to harbor genetic variations that influenced collateralization.

TNF-α receptor 1 knockdown in the subfornical organ ameliorates sympathetic excitation and cardiac hemodynamics in heart failure rats.

In systolic heart failure (HF), circulating proinflammatory cytokines upregulate inflammation and renin-angiotensin system (RAS) activity in cardiovascular regions of the brain, contributing to sympathetic excitation and cardiac dysfunction. Important among these is the subfornical organ (SFO), a forebrain circumventricular organ that lacks an effective blood-brain barrier and senses circulating humors. We hypothesized that the tumor necrosis factor-α (TNF-α) receptor 1 (TNFR1) in the SFO contributes to sympathetic excitation and cardiac dysfunction in HF rats. Rats received SFO microinjections of a TNFR1 shRNA or a scrambled shRNA lentiviral vector carrying green fluorescent protein, or vehicle. One week later, some rats were euthanized to confirm the accuracy of the SFO microinjections and the transfection potential of the lentiviral vector. Other rats underwent coronary artery ligation (CL) to induce HF or a sham operation. Four weeks after CL, vehicle- and scrambled shRNA-treated HF rats had significant increases in TNFR1 mRNA and protein, NF-κB activity, and mRNA for inflammatory mediators, RAS components and c-Fos protein in the SFO and downstream in the hypothalamic paraventricular nucleus, along with increased plasma norepinephrine levels and impaired cardiac function, compared with vehicle-treated sham-operated rats. In HF rats treated with TNFR1 shRNA, TNFR1 was reduced in the SFO but not paraventricular nucleus, and the central and peripheral manifestations of HF were ameliorated. In sham-operated rats treated with TNFR1 shRNA, TNFR1 expression was also reduced in the SFO but there were no other effects. These results suggest a key role for TNFR1 in the SFO in the pathophysiology of systolic HF.NEW & NOTEWORTHY Activation of TNF-α receptor 1 in the subfornical organ (SFO) contributes to sympathetic excitation in heart failure rats by increasing inflammation and renin-angiotensin system activity in the SFO and downstream in the hypothalamic paraventricular nucleus. Cytokine receptors in the SFO may be a target for central intervention in cardiovascular conditions characterized by peripheral inflammation.

The Values of Coronary Circulating miRNAs in Patients with Atrial Fibrillation.

The mechanism of miRNA regulation in atrial fibrillation (AF) occurrence and development is still unclear, especially, the regulating values of coronary circulating miRNAs has not been reported. Based on our AF radiofrequency ablation clinical practice and previous miRNA study, we proposed a hypothesis that the coronary circulating miRNA might much better reflect the regulating state and metabolic level of myocardial miRNA in AF patient. To investigate the regulating values of coronary circulation miRNA, 90 AF patients were selected and compared with 90 healthy subjects, the changes of coronary circulating miRNA differential expression profile in the whole genome were observed in this study. We found out that compared with autologous peripheral blood (PB), 6 miRNAs were upregulated and 8 miRNA downregulated in AF patients' coronary sinus blood (CSB) significantly, especially, the expression of miR-1266, miR-4279 and miR-4666a-3p were obviously increased. Compared with normal donors' peripheral blood, 16 miRNAs were upregulated and 24 miRNAs downregulated dramatically in patients' peripheral blood, among them, the miR-3171 decreased, but miR-892a and miR-3149 increased significantly from the early to end stages of AF. Our results indicated that the coronary circulating miRNA can really reflect the regulating values of miRNA in AF patient; the level of miRNA change in 3 types of AF may reflect the severity of AF clinical and pathophysiological advance; The miR-892a, miR-3171 and miR-3149 may be used as biomarkers for earlier diagnosis, while miR-1266, miR-4279 and miR-4666a-3p may serve as potential intervening targets for AF patient in future.

786T/c endothelial nitric oxide synthase gene polymorphism and coronary collateral circulation.

INTRODUCTION: In this study, we investigated the association between -786T/C polymorphism of the endothelial nitric oxide (NOS3) gene in which thymidine is replaced by a cytosine at nucleotide -786 (rs 2070744) and coronary collateral circulation (CCC) in patients with stable coronary artery disease. MATERIALS AND METHODS: 286 patients having a critical stenosis (> 95%) in at least one major epicardial coronary vessel were included in the study. CCC was defined according to the Rentrop classification (R). Patients with R0-1 CCC were included in the poor CCC group and subjects with R2-3 CCC were assigned to the good CCC group. The polymerase chain reaction method was used for genotyping. 152 patients with poor CCC and 134 patients with good CCC were examined. RESULTS: The frequency of cytosine-cytosine (CC) and thymidine-cytosine (TC) genotypes and allele C were higher in the poor CCC group, but the difference did not reach statistical significance. In the dominant model, the frequency of CC+TC vs. thymidine-thymidine (TT) genotypes was significantly higher in the poor CCC group (67.1% vs. 54.5%, respectively; χ²=4.78; p=0.02). In multivariate regression analysis, the dominant model for -786T/C polymorphism of the NOS3 gene remained as an independent correlate of poor CCC. DISCUSSION: -786T/C polymorphism of the NOS3 gene (rs 2070744) may be associated with poor angiogenesis and the development of CCC in stable coronary artery disease.

Sodium tanshinone IIA sulfonate ameliorates experimental coronary no-reflow phenomenon through down-regulation of FGL2.

AIMS: The effects of sodium tanshinone IIA sulfonate (STS) on coronary no-reflow (CNR) relevant to microvascular obstruction (MVO) remain unknown. Studies had shown that fibrinogen-like protein 2 (FGL2) expressed in microvascular endothelial cells (MECs) is a key mediator in MVO. Thus, we aimed to elucidate the roles of STS in CNR and relations between STS and FGL2. MAIN METHODS: Myocardial ischemia/reperfusion was selected to represent CNR model. The no-reflow zone and infarct area were assessed using Thioflavin S and TTC staining, and cardiac functional parameters were detected using echocardiography. Western blot was used to detected FGL2 level, fibrin level, protease-activated receptor-1 (PAR-1) activation and inflammation cells infiltration. FGL2 and inflammation cells were also identified by IHC. Microthrombus was detected by Carstairs' and MSB staining. We also detected the roles of STS on FGL2 expression, thrombin generation, phospho-Akt and NF-κB levels in MECs. KEY FINDINGS: Upon treatment with STS in CNR model, the no-reflow and infarct areas decreased significantly and cardiac function improved. The FGL2 expression was inhibited by STS in vivo as well as in vitro with thrombin generation inhibition. In addition, STS up-regulates Akt phosphorylation and suppressed NF-κB expression in activated MECs. Furthermore, fibrin deposition, PAR-1 activation and inflammatory response were inhibited with STS administration in CNR model. SIGNIFICANCE: Our results displayed a novel pharmacological action of STS on CNR. STS is able to ameliorate CNR through inhibition of FGL2 expression mediated by Akt and NF-κB pathways as well as prevention of MVO by suppressing fibrin deposition and inflammation.

Mitochondrial Aldehyde Dehydrogenase 2 Regulates Revascularization in Chronic Ischemia: Potential Impact on the Development of Coronary Collateral Circulation.

OBJECTIVE: Revascularization is an essential process to compensate for cardiac underperfusion and, therefore, preserves cardiac function in the face of chronic ischemic injury. Recent evidence suggested a vital role of aldehyde dehydrogenase 2 (ALDH2) in cardiac protection after ischemia. This study was designed to determine whether ALDH2 regulates chronic ischemia-induced angiogenesis and to explore the underlying mechanism involved. Moreover, the clinical impact of the ALDH2 mutant allele on the development of coronary collateral circulation (CCC) was evaluated. APPROACH AND RESULTS: Mice limb ischemia was performed. Compared with wild-type, ALDH2 deletion significantly reduced perfusion recovery, small artery and capillary density, and increased muscle atrophy in this ischemic model. In vitro, ALDH2-knockdown reduced proliferation, migration and hypoxia triggered endothelial tube formation of endothelial cells, the effects of which were restored by ALDH2 transfection. Further examination revealed that ALDH2 regulated angiogenesis possibly through hypoxia-inducible factor-1α/vascular endothelial growth factor pathways. To further discern the role of ALDH2 deficiency in the function of bone marrow stem/progenitor cells, cross bone marrow transplantation was performed between wild-type and ALDH2-knockout mice. However, there was no significant improvement for wild-type bone marrow transplantation into knockout mice. ALDH2 genotyping was screened in 139 patients with chronic total occlusion recruited to Zhongshan Hospital (2011.10-2014.4). Patients with poor CCC (Rentrop 0-1; n=51) exhibited a higher frequency of the AA genotype than those with enriched CCC (Rentrop 2-3; n=88; 11.76% versus 1.14%; P=0 0.01). However, the AA group displayed less enriched CCC frequency in Logistic regression model when compared with the GG group (odds ratio=0.08; 95% confidence interval, 0.009-0.701; P=0 0.026). Furthermore, serum vascular endothelial growth factor level tended to be lower in patients with ALDH2 mutation. CONCLUSIONS: This study demonstrated that ALDH2 possesses an intrinsic capacity to regulate angiogenesis via hypoxia-inducible factor-1α and vascular endothelial growth factor. Patients with ALDH2-deficient genotype displayed a higher risk of developing poor CCC. Therapeutic individualization based on ALDH2 allele distribution may thus improve the therapeutic benefit, especially in the East Asian decedents.

Cardiomyocyte A Disintegrin And Metalloproteinase 17 (ADAM17) Is Essential in Post-Myocardial Infarction Repair by Regulating Angiogenesis.

BACKGROUND: A disintegrin and metalloproteinase 17 (ADAM17) is a membrane-bound enzyme that mediates shedding of many membrane-bound molecules, thereby regulating multiple cellular responses. We investigated the role of cardiomyocyte ADAM17 in myocardial infarction (MI). METHODS AND RESULTS: Cardiomyocyte-specific ADAM17 knockdown mice (ADAM17(flox/flox)/α-MHC-Cre; f/f/Cre) and parallel controls (ADAM17(flox/flox); f/f) were subjected to MI by ligation of the left anterior descending artery. Post MI, f/f/Cre mice showed compromised survival, higher rates of cardiac rupture, more severe left ventricular dilation, and suppressed ejection fraction compared with parallel f/f-MI mice. Ex vivo ischemic injury (isolated hearts) resulted in comparable recovery in both genotypes. Myocardial vascular density (fluorescent-labeled lectin perfusion and CD31 immunofluorescence staining) was significantly lower in the infarct areas of f/f/Cre-MI compared with f/f-MI mice. Activation of vascular endothelial growth factor receptor 2 (VEGFR2), its mRNA, and total protein levels were reduced in infarcted myocardium in ADAM17 knockdown mice. Transcriptional regulation of VEGFR2 by ADAM17 was confirmed in cocultured cardiomyocyte-fibroblast as ischemia-induced VEGFR2 expression was blocked by ADAM17-siRNA. Meanwhile, ADAM17-siRNA did not alter VEGFA bioavailability in the conditioned media. ADAM17 knockdown mice (f/f/Cre-MI) exhibited reduced nuclear factor-κB activation (DNA binding) in the infarcted myocardium, which could underlie the suppressed VEGFR2 expression in these hearts. Post MI, inflammatory response was not altered by ADAM17 downregulation. CONCLUSIONS: This study highlights the key role of cardiomyocyte ADAM17 in post-MI recovery by regulating VEGFR2 transcription and angiogenesis, thereby limiting left ventricular dilation and dysfunction. Therefore, ADAM17 upregulation, within the physiological range, could provide protective effects in ischemic cardiomyopathy.

Salient features of the coronary collateral circulation and its clinical relevance.

The coronary collateral circulation provides an alternative source of blood supply to myocardium jeopardised by ischaemia. Collaterals enlarge with obstructive coronary artery disease to allow bulk flow, but blood flow deliverable by the native, pre-formed collateral extent can already be sizeable. Genetic determinants contribute significantly to the wide variability observed in both native collateral extent and its capacity to enlarge, and the severity of the coronary stenosis is the most significant environmental determinant for collateral enlargement. The protective effect of a well-developed coronary collateral circulation translates into relevant improvements in all-cause and cardiac mortality in the acute and chronic phases of coronary artery disease, as well as into a reduction of future adverse cardiovascular events.

Effects of age and caloric restriction on the cardiac and coronary response to endothelin-1 in rats.

BACKGROUND AND AIMS: Aging is associated with alterations in the cardiovascular system such as increased vasoconstriction and decreased vasodilatation. Some of these changes are partially reversed by caloric restriction. Endothelin-1 is a potent vasoconstrictor which levels increased with age. The aim of this study is to analyze the role of endothelin-1 in the cardiac and coronary changes induced by age and whether these changes may be attenuated by a three-month caloric restriction. METHODS AND RESULTS: Hearts from young (3 months old), aged (24 months old) and aged rats after 3 months of caloric restriction were perfused according to the Langendorff technique. Coronary vasoconstriction to endothelin-1 was reduced in old rats, and endothelin-1 increased myocardial contractility (dP/dt) and heart rate in old but not in young rats. These changes observed in old rats were partly reversed by caloric restriction. Also, in the myocardial tissue of old rats the gene expression of endothelin-1, inducible nitric oxide synthase (iNOS) and tumor necrosis factor alpha (TNF-a) was increased, and the gene expression of endothelin ETB receptors and endothelial nitric oxide syntase (eNOS) was reduced, compared with young rats. Aging induced changes in the expression of ETB receptors and eNOS were reversed by caloric restriction. CONCLUSIONS: These results suggest that aging produces alterations in myocardial and coronary responses to endothelin-1, that may be related to changes in expression of nitric oxide synthases and/or endothelin receptor subtypes, with some of these changes being prevented by caloric restriction.

Intercellular adhesion molecule-1 K469E and angiotensinogen T207M polymorphisms in coronary slow flow.

OBJECTIVE: To investigate intercellular adhesion molecule-1 (ICAM1) and angiotensinogen (AGT) gene polymorphisms, as related to atherosclerosis and endothelial dysfunction, in coronary slow flow (CSF). SUBJECTS AND METHODS: The participants in this study were 48 patients with CSF and 67 patients with normal coronary flow as controls. The K469E polymorphism of ICAM1 (rs5498) and the T207M polymorphism of AGT (rs4762) were determined using the polymerase chain reaction amplification method. RESULTS: Baseline demographic parameters were similar in both groups. The mean thrombolysis in myocardial infarction frame count was significantly higher in patients with CSF (23.8 ± 5.1) compared to the controls (13.3 ± 2.6, p < 0.001). A significant association was found between the ICAM1 K allele and CSF (OR: 1.96, 95% CI: 1.15-3.35, p = 0.013). There was no difference in the frequency of AGT T207M genotypes in the patients with CSF and the control subjects. CONCLUSION: This study showed that K469E polymorphisms of ICAM1 that play a role in atherosclerotic pathogenesis are related to CSF.

Single nucleotide polymorphisms associated with abnormal coronary microvascular function.

BACKGROUND: Single nucleotide polymorphisms (SNPs) are the most common source of genetic variation. Although microvascular pathology is associated with cardiovascular events, genetic phenotypes causing microvascular disease remain largely unknown. This study identifies sex-specific SNPs associated with coronary microvascular dysfunction. METHODS AND RESULTS: Six hundred and forty-three patients without significant obstructive coronary heart disease were enrolled, referred for cardiac catheterization, and underwent invasive coronary microcirculatory assessment. Patient data were collected from 1529 autosomal SNPs and seven X chromosome SNPs, which were selected to represent the variability from 76 candidate genes with published associations with coronary vasoreactivity, angiogenesis, inflammation, vascular calcification, atherosclerosis risk factors, female hormones, blood coagulation, or coronary heart disease. Coronary flow reserve (CFR) was assessed by an intracoronary injection of adenosine. Patients were categorized according to a CFR above or below 2.5 and were stratified by sex.After adjusting for age, sex, and BMI, this study shows that SNPs within VEGFA and CDKN2B-AS1 are associated with abnormal CFR (P<0.005). SNPs within MYH15, VEGFA, and NT5E are associated with abnormal CFR in men. No SNPs were associated with abnormal CFR in women. CONCLUSION: Genetic variations within defined regions of VEGFA and CDKN2B-AS1 genes are associated with coronary microvascular dysfunction. Furthermore, sex-specific allelic variants within MYH15, VEGFA, and NT5E are associated with an increased risk of coronary microvascular dysfunction in men.

Association between the Glu298Asp and 4b/4a polymorphisms of endothelial nitric oxide synthase and coronary slow flow in the North Indian population.

RATIONALE: Genetic variants in endothelial nitric oxide synthase gene (NOS3) leading to endothelial dysfunction may be predispose to the coronary slow-flow phenomenon (CSFP). METHODS AND RESULTS: In this study, we examined the relationship between Glu298Asp (894G/T) and 4b/4a polymorphisms of NOS3 and CSFP. A total of 27 patients with CSFP but otherwise normal coronary arteries (mean age 50.4±8.2 years) and 200 controls with a normal coronary angiogram (mean age 53.1±8.6 years) were screened for Glu298Asp and 4b/4a polymorphisms by restriction fragment length polymorphism and PCR, respectively. Nitric oxide levels were determined using Griess' enzymatic method for an association with the polymorphisms. The genotype distribution of the Glu298Asp polymorphism differed significantly between the CSFP patients and controls (P=0.004). The dominant genetic model showed that GT+TT was significantly prevalent in patients in comparison with controls (P=0.014) and the T allele was significantly prevalent in patients (P=0.002). The genetic distribution of 4b/4a differed significantly for the heterozygous genotype ba (P=0.047). The overdominant genetic model re-established that the ba genotype was significantly prevalent in patients (P=0.044). Nitric oxide level was higher in patients than in controls, the values being 144.51±43.25 and 129.64±29.47 µmol/l, respectively (P>0.05). The genotypes of Glu298Asp showed a trend of association with nitric oxide levels, which decreased linearly in the order of GG, GT, and TT (P>0.05). CONCLUSION: The Glu298Asp polymorphism of NOS3 associates with CSFP.

Endothelial function and germ-line ACE I/D, eNOS and PAI-1 gene profiles in patients with coronary slow flow in the Canakkale population: multiple thrombophilic gene profiles in coronary slow flow.

BACKGROUND: We examined the effects of ACE, PAI-1 and eNOS gene polymorphisms on endothelial function. The genes are related to atherosclerosis and endothelial dysfunction in coronary slow flow (CSF). METHODS: Thirty-three patients with angiographically proven CSF and 48 subjects with normal coronary flow were enrolled in this study. Coronary flow patterns were determined by the thrombolysis in myocardial infarction (TIMI) frame count method. Endothelial function was assessed in the brachial artery by endothelium-dependent flow-mediated dilatation (FMD). PAI-1 4G/5G, eNOS T-786C and ACE I/D polymorphisms were determined by polymerase chain reaction (PCR) amplification. RESULTS: No difference was found between the groups regarding age, heart rate and blood pressure. Males were more prevalent among patients with CSF than control subjects (58.8 vs 29.8%, p = 0.009). Mean TIMI frame counts were significantly higher in CSF patients (24.2 ± 4.0 vs 13.1 ± 2.5 fpm, p = 0.001). FMD was significantly lower in CSF patients than in the controls (4.9 ± 6.6 vs 7.9 ± 5.6%, p = 0.029). TIMI frame count and FMD were found to be negatively correlated in a correlation analysis (r = -0.269, p = 0.015). PAI-1 4G/5G, eNOS T-786C and ACE I/D polymorphisms were similar in the two groups. CONCLUSIONS: This study showed that endothelial function was impaired in patients with CSF. PAI-1, ACE and eNOS polymorphisms were not related to CSF in our study population.

Determinants of human coronary collaterals.

The human coronary collateral circulation is prognostically relevant. The understanding of collateral formation and its determinants may guide future therapeutic strategies aiming at promoting collateral growth and functionality, and hence reducing the global burden of coronary artery disease (CAD).

Role of genetic polymorphisms of ion channels in the pathophysiology of coronary microvascular dysfunction and ischemic heart disease.

Conventionally, ischemic heart disease (IHD) is equated with large vessel coronary disease. However, recent evidence has suggested a role of compromised microvascular regulation in the etiology of IHD. Because regulation of coronary blood flow likely involves activity of specific ion channels, and key factors involved in endothelium-dependent dilation, we proposed that genetic anomalies of ion channels or specific endothelial regulators may underlie coronary microvascular disease. We aimed to evaluate the clinical impact of single-nucleotide polymorphisms in genes encoding for ion channels expressed in the coronary vasculature and the possible correlation with IHD resulting from microvascular dysfunction. 242 consecutive patients who were candidates for coronary angiography were enrolled. A prospective, observational, single-center study was conducted, analyzing genetic polymorphisms relative to (1) NOS3 encoding for endothelial nitric oxide synthase (eNOS); (2) ATP2A2 encoding for the Ca²âº/H⁺-ATPase pump (SERCA); (3) SCN5A encoding for the voltage-dependent Na⁺ channel (Nav1.5); (4) KCNJ8 and KCNJ11 encoding for the Kir6.1 and Kir6.2 subunits of K-ATP channels, respectively; and (5) KCN5A encoding for the voltage-gated K⁺ channel (Kv1.5). No significant associations between clinical IHD manifestations and polymorphisms for SERCA, Kir6.1, and Kv1.5 were observed (p > 0.05), whereas specific polymorphisms detected in eNOS, as well as in Kir6.2 and Nav1.5 were found to be correlated with IHD and microvascular dysfunction. Interestingly, genetic polymorphisms for ion channels seem to have an important clinical impact influencing the susceptibility for microvascular dysfunction and IHD, independent of the presence of classic cardiovascular risk factors.

Evaluation of coronary microvascular function and nitric oxide synthase intron 4a/b polymorphism in patients with coronary slow flow.

OBJECTIVE: Slow coronary flow (SCF) is reported to be associated with increased risk of cardiovascular disease. We have used coronary flow reserve measurement by transthoracic Doppler echocardiography to determine coronary microvascular function in patients with SCF and to determine whether the intron 4a/b polymorphism of the eNOS gene influences coronary endothelial function. METHODS: Overall, 96 patients with SCF and 79 controls were enrolled in the study. Coronary flow was quantified according to the thrombolysis in myocardial infarction (TIMI) frame count (TFC) on angiogram. Coronary diastolic peak flow velocities (DPFV) were measured with color Doppler flow mapping at baseline and after dipyridamole infusion. Coronary flow reserve was calculated as the ratio of hyperemic to baseline DPFV. The eNOS 4a/b polymorphism was detected by PCR. Patients with diabetes were excluded from the study. RESULTS: The SCF group was comparable to the control group in terms of demographic and clinical characteristics, except for hemoglobin and HDL-cholesterol levels, TFC of the left anterior descending artery, the circumflex artery, and the right coronary artery; the mean TFC was higher in the SCF group. Hyperemic DPFV and the hyperemic/baseline DPFV ratio were significantly lower in the SCF group when compared with the control group. However, baseline DPFV were similar in both groups. The number of patients with eNOS4 a/a and eNOS4 a/b phenotypes was statistically higher in SCF groups. The frequency of allele 'a' of the eNOS4 gene was also statistically higher in the SCF group. When patients were grouped according to the presence or absence of allele 'a' of the eNOS4 gene, statistically significant differences were found in the TFC of the left anterior descending artery, the circumflex artery; mean TFC; baseline DPFV; and hyperemic/baseline DPFV. Univariate analysis in which eNOS4 b/b was used as the referent group showed that the presence of allele 'a' of the eNOS4 gene significantly predicted SCF (odds ratio: 2.79, 95% confidence interval: 1.32-5.89; P=0.007). In multivariate analysis using a model adjusted for variables with a P value lower than 0.10 in univariate analyses, the presence of allele 'a' of the eNOS4 gene was found to be an independent predictor of SCF (odds ratio: 3.22, 95% confidence interval: 1.28-8.82; P=0.013). CONCLUSION: The presence of allele 'a' may be a risk factor for microvascular endothelial dysfunction and higher TFCs in SCF patients.

Coronary vasospasm induced in transgenic mouse with increased phospholipase C-δ1 activity.

BACKGROUND: We reported that phospholipase C (PLC)-δ1 activity was enhanced 3-fold in patients with coronary spastic angina. We detected variant PLC-δ1 with replacement of arginine 257 by histidine (R257H) showing increased enzymatic activity. We tested the hypothesis that increased PLC-δ1 activity causes enhanced coronary vasomotility. METHODS AND RESULTS: We generated transgenic (TG) mice with human R257H variant PLC-δ1 in vascular smooth muscle cells. PLC enzymatic activity in the coronary artery was increased by 2.57 and 1.89 times, respectively, in homozygous and heterozygous TG compared with wild-type (WT) mice. ST elevation after ergometrine occurred in 17 of 18 homozygous TG, 6 of 20 heterozygous TG, and 3 of 22 WT mice (P<0.01, homozygous TG versus WT; P<0.05, homozygous TG versus heterozygous TG; P=NS, heterozygous TG versus WT). ST elevation was associated with bradyarrhythmias in homozygous TG mice. Focal coronary artery narrowing was documented with the microvascular filling technique in 3 of 5 homozygous TG mice after ergometrine but not in any of 7 WT mice (P<0.05). In the isolated Langendorff hearts, coronary perfusion pressure was increased after ergometrine in homozygous TG mice (P<0.01) but not in heterozygous TG or WT mice. Coronary perfusion pressure increase after prostaglandin F2α was similar among homozygous TG, heterozygous TG, and WT mice. Cultured rat aortic smooth muscle cells transfected with variant PLC-δ1 showed a higher PLC activity than those with WT PLC-δ1 (P<0.05) and furthermore showed greater intracellular Ca2+ response to acetylcholine in variant than in WT PLC-δ1 (P<0.05). CONCLUSIONS: Increased PLC-δ1 activity enhances coronary vasomotility such as that seen in patients with coronary spastic angina.

Adenosine A2(A) receptor gene polymorphism (1976C>T) affects coronary flow reserve response during vasodilator stress testing in patients with non ischemic-dilated cardiomyopathy.

OBJECTIVES: Patients with non ischemic-dilated cardiomyopathy (DCM) are characterized by an activation of the adenosinergic system and reduced coronary flow reserve (CFR) evaluated by transthoracic Doppler echocardiography during vasodilator adenosinergic stress (dipyridamole administration). The aim of this study was to assess whether genetic polymorphisms (263C>T and 1976C>T) of the A2(A) receptor gene affect CFR response in patients with DCM. METHODS: We enrolled a group of 80 patients with DCM (55 male; age, 62±10.3 years) and 162 healthy volunteers (55 male; age, 45.1±9.5 years). Doppler-derived CFR (high-dose dipyridamole coronary diastolic peak flow velocity to resting coronary peak flow velocity ratio) of distal left anterior descending artery was determined in DCM. A2(A) receptor genotyping was determined in all patients by polymerase chain reaction-restriction fragment length polymorphism analysis. The expression of A2(A) protein and mRNA was also assessed in healthy controls. RESULTS: The genotype distribution of the 263C>T (P=0.5) and 1976C>T (P=0.8) polymorphisms was not significantly different between patients and controls. Patients with 1976TT genotype had significantly lower CFR value than 1976CC patients (2.3±0.7, 2.0±0.5 and 1.9±0.4, P<0.05 for CC, CT and TT genotypes, respectively). Controls who were heterozygous (P=0.02) or homozygous (P=0.001) for the T1976 allele showed a significant increase in A2(A) receptor protein. CONCLUSION: These data demonstrate that A2(A) 1976C>T polymorphism is associated with a blunted coronary vasodilatory response in patients with DCM, and support a direct consequences of this single nucleotide polymorphism for protein expression. Additional studies are needed to better define the functional role of this genetic variant as well as to clarify the potential clinical impact of genetics during pharmacological stress cardiac imaging.

Hearts of hypoxia-inducible factor prolyl 4-hydroxylase-2 hypomorphic mice show protection against acute ischemia-reperfusion injury.

Hypoxia-inducible factor (HIF) has a pivotal role in oxygen homeostasis and cardioprotection mediated by ischemic preconditioning. Its stability is regulated by HIF prolyl 4-hydroxylases (HIF-P4Hs), the inhibition of which is regarded as a promising strategy for treating diseases such as anemia and ischemia. We generated a viable Hif-p4h-2 hypomorph mouse line (Hif-p4h-2(gt/gt)) that expresses decreased amounts of wild-type Hif-p4h-2 mRNA: 8% in the heart; 15% in the skeletal muscle; 34-47% in the kidney, spleen, lung, and bladder; 60% in the brain; and 85% in the liver. These mice have no polycythemia and show no signs of the dilated cardiomyopathy or hyperactive angiogenesis observed in mice with broad spectrum conditional Hif-p4h-2 inactivation. We focused here on the effects of chronic Hif-p4h-2 deficiency in the heart. Hif-1 and Hif-2 were stabilized, and the mRNA levels of glucose transporter-1, several enzymes of glycolysis, pyruvate dehydrogenase kinase 1, angiopoietin-2, and adrenomedullin were increased in the Hif-p4h-2(gt/gt) hearts. When isolated Hif-p4h-2(gt/gt) hearts were subjected to ischemia-reperfusion, the recovery of mechanical function and coronary flow rate was significantly better than in wild type, while cumulative release of lactate dehydrogenase reflecting the infarct size was reduced. The preischemic amount of lactate was increased, and the ischemic versus preischemic [CrP]/[Cr] and [ATP] remained at higher levels in Hif-p4h-2(gt/gt) hearts, indicating enhanced glycolysis and an improved cellular energy state. Our data suggest that chronic stabilization of Hif-1alpha and Hif-2alpha by genetic knockdown of Hif-p4h-2 promotes cardioprotection by induction of many genes involved in glucose metabolism, cardiac function, and blood pressure.