Eisaku Harada

Association of the Missense Glu298Asp Variant of the Endothelial Nitric Oxide Synthase Gene With Myocardial Infarction

OBJECTIVES We examined the possible association between the missense Glu298Asp variant of the endothelial nitric oxide synthase (eNOS) gene and myocardial infarction (MI). BACKGROUND Endothelium-derived nitric oxide (NO) plays a key role in the regulation of vascular tone. Recently, we reported that a missense Glu298Asp variant in exon 7 of the eNOS gene is a possible genetic factor involved in the pathogenesis of coronary spasm. Endothelium-derived NO also has vasoprotective effects by suppressing platelet aggregation, leukocyte adhesion and smooth muscle cell proliferation. METHODS We screened 285 patients with an MI and 607 control subjects in Kumamoto Prefecture, Japan. Genotypes were determined by polymerase chain reaction-restriction fragment-length polymorphism analysis. RESULTS The frequency of the missense Glu298Asp variant was significantly higher in the MI group than in the control group (21.1% vs. 13.3%, p = 0.003, odds ratio 1.73 for the dominant effect of the eNOS T allele). Multiple logistic regression analysis showed that the missense Glu298Asp variant was an independent risk factor for MI, as was diabetes mellitus, hypertension, cigarette smoking, hypercholesterolemia and body mass index. CONCLUSIONS There was a significant association of the missense Glu298Asp variant of the eNOS gene with MI. This marker-disease association may be due to the impaired effects of NO on the cardiovascular system: dysregulation of vascular tone, platelet aggregation and leukocyte adhesion and smooth muscle cell proliferation, all of which promote coronary atherosclerosis and thrombosis.

Aldosterone Production Is Activated in Failing Ventricle in Humans

Background—Recent reports have indicated that aldosterone is produced in extra-adrenal tissues in animals. The present study was designed to examine whether aldosterone is produced in human heart. Methods and Results—Plasma levels of aldosterone, BNP, and angiotensin-converting enzyme were measured in anterior interventricular vein (AIV), coronary sinus (CS), and aortic root (Ao), respectively, in 20 patients with left ventricular systolic dysfunction (LVSD), 25 patients with LV diastolic dysfunction (LVDD), and 23 control subjects. Aldosterone levels were significantly higher in AIV and CS than Ao in LVSD (98±10 versus 72±9 pg/mL, P <0.001, and 97±11 versus 72±9 pg/mL, P <0.001, respectively) and LVDD (87±10 versus 71±9 pg/mL, P <0.01, and 84±10 versus 71±9 pg/mL, P <0.01, respectively) groups, but no differences were observed in levels for these sites in the control group. Levels of ACE activity and BNP also were higher in AIV than Ao in both LV dysfunction groups. The difference in aldosterone levels between AIV and Ao and those in BNP and angiotensin-converting enzyme had a significant positive correlation with LVEDP and a significant negative correlation with LV ejection fraction in the LVSD group. Conclusions—Production of aldosterone, angiotensin-converting enzyme, and BNP are activated in failing human ventricle in proportion to severity.

Coronary artery spasm—-Clinical features, diagnosis, pathogenesis, and treatment

Coronary (artery) spasm plays an important role in the pathogenesis of ischemic heart disease, including stable angina, unstable angina, myocardial infarction, and sudden death. The prevalence of coronary spasm differs among populations, is higher in Japan and Korea than in the Western countries probably due to genetic as well as environmental factors. Coronary spasm occurs most often from midnight to early morning and is usually not induced by exercise in the daytime. The attacks of coronary spasm are associated with either ST segment elevation or depression, or negative U wave on ECG. Patients with multi-vessel coronary spasm may suffer from lethal arrhythmia, including advanced AV block, ventricular tachycardia or fibrillation, or even sudden death, and they are often resistant to conventional medical therapy including Ca-channel blockers (CCBs). Endothelial nitric oxide (NO) activity is reduced and markers of oxidative stress are elevated in patients with coronary spasm. Thrombogenesis is enhanced and plasma levels of hsCRP and P-selection are elevated in patients with coronary spasm. Thus, patients with coronary spasm have endothelial dysfunction and are suffering from a low-grade chronic inflammation. Polymorphisms of endothelial NO synthase, smoking, and low-grade inflammation are the most important risk factors for coronary spasm. Coronary spasm is a hyper-contraction of coronary smooth muscle triggered by an increase of intracellular Ca2+ in the presence of an increased Ca2+ sensitivity. It has been shown that RhoA/ROCK pathway is involved in Ca2+ sensitivity and that the reduced endothelial NO activity results in increased Ca2+ sensitivity through enhanced RhoA/ROCK pathway. Accordingly, it is possible that in addition to CCBs, RhoA/ROCK pathway blockers may prove to be useful for the treatment of coronary spasm.

Aldosterone Induces Angiotensin-Converting-Enzyme Gene Expression in Cultured Neonatal Rat Cardiocytes

Background—The cardiac renin-angiotensin-aldosterone system is activated in failing hearts in proportion to the severity of the disease. We hypothesized that a positive feedback mechanism might exist within this system and contribute to the progression of the heart failure. Methods and Results—To test this hypothesis, we examined whether angiotensin II or aldosterone induces the expression of angiotensin-converting-enzyme (ACE) mRNA in cultured neonatal rat ventricular cardiocytes. Expression of ACE mRNA was detected and quantified using real-time reverse transcription-polymerase chain reaction. Exposure to angiotensin II (10−5 mol/L) for 24 hours had no significant effect on the expression of ACE mRNA (0.7±0.5-fold versus control, P =NS), but similar treatment with aldosterone (10−5 mol/L) induced a 23.3±7.9-fold increase (P <0.01) in ACE mRNA expression. The effect of aldosterone was both time- (maximal effect, 24 hours) and dose-dependent (EC50, 4×10−7 mol/L), and it was significantly (P <0.01) inhibited by spironolactone, a specific mineralocorticoid receptor antagonist. Conclusions—Aldosterone upregulates ACE mRNA expression, which is blocked by spironolactone in neonatal rat cardiocytes. Thus, spironolactone may suppress the progression of heart failure by blocking the effects of aldosterone and angiotensin II.

Plasma Level of B-Type Natriuretic Peptide as a Prognostic Marker After Acute Myocardial Infarction A Long-Term Follow-Up Analysis

BACKGROUND Circulating levels of B-type natriuretic peptide (BNP), a cardiac hormone, reflect the severity of cardiac dysfunction. Because the plasma BNP level changes dramatically during the period after the onset of acute myocardial infarction (AMI), identification of a suitable sampling time is problematic. There have been several reports indicating that the plasma BNP level obtained in the acute phase of AMI can be used as a prognostic marker. We examined whether the plasma BNP level measured 3 to 4 weeks after the onset of AMI represents a reliable prognostic marker for patients with AMI. METHODS AND RESULTS We analyzed 145 consecutive patients with AMI. Plasma BNP levels were measured during the 3 to 4 weeks after onset of AMI. Of those patients, 23 experienced fatal cardiac events during this study. The mean follow-up period was 58.6 months. Log BNP, left ventricular end-diastolic pressure, and pulmonary vascular resistance were all significantly higher in the cardiac death group, and there were more men and more patients with a history of heart failure in the cardiac death group. A Cox proportional hazards model analysis showed that log BNP was an independent predictor of cardiac death. The survival rate was significantly higher in patients with log BNP <2.26 (180 pg/mL) than in those with log BNP > or =2.26. CONCLUSIONS The plasma BNP level obtained 3 to 4 weeks after the onset of AMI can be used as an independent predictor of cardiac death in patients with AMI.

Effects of a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, fluvastatin, on coronary spasm after withdrawal of calcium-channel blockers.

OBJECTIVES The purpose of this study was to determine whether a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin) suppresses coronary spasm. BACKGROUND Coronary spasm is associated with endothelial dysfunction. Statins have been shown to improve endothelial function. METHODS This was a prospective, randomized, open-label, end point study. Sixty-four patients who had no significant organic coronary stenosis and in whom coronary spasm was induced by intracoronary injection of acetylcholine (ACh) were randomly assigned to fluvastatin 30 mg/day plus the conventional calcium-channel blocker (CCB) therapy (31 patients, statin group) or the conventional CCB therapy (33 patients, nonstatin group). After 6 months of treatment, the intracoronary injection of ACh was repeated and the coronary spasm was assessed. RESULTS Coronary spasm was suppressed in 16 of the 31 patients (51.5%, p < 0.0001) of the statin group and in 7 of the 33 patients (21.2%, p = 0.0110) of the nonstatin group after 6 months of treatment. Thus, the number of patients with ACh-induced coronary spasm was significantly reduced in the statin group as compared with the nonstatin group (51.6% vs. 21.2%, p = 0.0231) after 6 months of treatment. CONCLUSIONS The addition of fluvastatin 30 mg/day to the conventional CCB therapy for 6 months significantly reduced the number of patients with ACh-induced coronary spasm as compared with the conventional CCB therapy. Thus, a statin (fluvastatin) may possibly be a novel therapeutic drug for coronary spasm.

Aldosterone Is Produced From Ventricles in Patients With Essential Hypertension

This study was designed to examine whether aldosterone is produced from the hearts of patients with essential hypertension without left ventricular systolic dysfunction (LVSD). The study population consisted of 20 patients with essential hypertension without LVSD and 22 control subjects. Plasma levels of aldosterone, serum ACE activity, and B-type natriuretic peptide levels were measured in the anterior interventricular vein (AIV), coronary sinus, and aortic root during cardiac catheterization. The plasma aldosterone levels were significantly higher in AIV and coronary sinus than in aortic root (99±11 versus 88±10 pg/mL, P <0.01, and 100±12 versus 88±10 pg/mL, P <0.01, respectively) in the hypertension group. On the other hand, there were no significant differences in aldosterone levels for these sites in the control group. There were no significant differences in ACE activity levels between aortic root, AIV, and coronary sinus in either the hypertension or control group. The levels of B-type natriuretic peptide were significantly higher in AIV than in aortic root in both groups. The difference in aldosterone levels between AIV and aortic root (&Dgr; Aldo[AIV−Ao]) had a significant positive correlation with the difference in ACE activity between AIV and aortic root (&Dgr;ACE[AIV−Ao]) (r =0.501, P <0.05) in the hypertension group. Both &Dgr; Aldo[AIV−Ao] and &Dgr;ACE[AIV−Ao] had a significant positive correlation with diastolic blood pressure (r =0.498, P <0.05;r =0.577, P <0.01, respectively) in the hypertension group. We conclude that production of aldosterone is activated in the left ventricles in patients with essential hypertension without LVSD in proportion to the severity of hypertension.

Inhibitory effect of natriuretic peptides on aldosterone synthase gene expression in cultured neonatal rat cardiocytes

Background—Although previously thought to be synthesized solely in adrenal cortex, we have recently showed that aldosterone is also produced in and the expression of CYP11B2 mRNA was induced in the failing or hypertensive human ventricle. Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are cardiac hormones with wide biological effects, including inhibition of renin and aldosterone production. We hypothesized that natriuretic peptides reduce the expression of CYP11B2 mRNA in the heart. Methods and Results—To test this hypothesis, we examined whether endogenous or exogenous natriuretic peptides reduce the expression of CYP11B2 mRNA using real-time reverse transcription-polymerase chain reaction. By using HS 142–1, a functional guanylyl cyclase-A type receptor antagonist, we showed that angiotensin II (AngII) pretreated with HS 142–1 increased CYP11B2 mRNA expression (1.62±0.12-fold, HS 142–1+AngII 10−7 mol/L versus AngII 10−7 mol/L alone, P <0.0001). The treatment with exogenous (10−6 mol/L) ANP and BNP reduced CYP11B2 mRNA expression (ANP, P =0.0042; BNP, P =0.0012). Conclusions—We showed that endogenous and exogenous natriuretic peptides reduced CYP11B2 mRNA expression in cultured neonatal rat cardiocytes. This may inhibit the cardiac renin-angiotensin-aldosterone system by suppressing the gene expression of CYP11B2 and restraining cardiac hypertrophy and fibrosis.

Plasma levels of A- and B-type natriuretic peptides in patients with hypertrophic cardiomyopathy or idiopathic dilated cardiomyopathy

We investigated the relation between left ventricular structure and the secretion patterns of A- and B-type natriuretic peptides (ANP and BNP) by comparing their plasma levels in patients with hypertrophic cardiomyopathy (HC) and patients with idiopathic dilated cardiomyopathy (IDC). The secretion of ANP and BNP was much higher in patients with HC than in those with IDC; this shows that left ventricular cavity size is a key factor that regulates the secretion of ANP and BNP.

Possible Association of Heart Failure Status With Synthetic Balance Between Aldosterone and Dehydroepiandrosterone in Human Heart

Background—Aldosterone is produced not only in the adrenal gland but also in the extra-adrenal tissues, including failing human heart. This study examined the production of dehydroepiandrosterone (DHEA) in human heart and elucidated the possible physiological significance. Method and Results—Using left ventricular tissues obtained at autopsy, reverse transcription–polymerase chain reaction followed by Southern blot analysis revealed the gene expressions of CYP17. By measuring plasma aldosterone and DHEA levels at the coronary sinuses and aortic roots during cardiac catheterization, we found that DHEA but not aldosterone was secreted from control subjects (P<0.0001 and P=0.74, respectively), whereas aldosterone but not DHEA was secreted from patients with heart failure (P=0.0017 and P=0.67, respectively). To examine the significance of DHEA, we measured myocyte cell sizes and the gene expression of B-type natriuretic peptide (BNP), using a neonatal rat cardiocyte culture system. We found that DHEA (10−8 mol/L) significantly inhibited the increase in myocyte cell sizes and BNP mRNA levels upregulated by endothelin-1 (P=0.031 and P<0.0001, respectively). Conclusions—CYP17 gene expression and production of DHEA were demonstrated in human control heart. Also, we found that cardiac production of DHEA was suppressed in failing heart. We postulated that DHEA and/or its metabolites exert a cardioprotective action through antihypertrophic effects.