Cardiac effects of acute administration of a protonophore in a rat model.

OBJECTIVES: Excessive use of uncoupling agents, previously used as weight loss agents, has led to the increase in body temperature and death. The aim of the present study was to evaluate the acute cardiac effects of mitochondrial protonophore in a rat model at a high dose, and its specific influence on cardiac substrate uptake. METHODS: Eight-week-old male Sprague-Dawley rats were intraperitoneally injected with the protonophore carbonyl cyanide m-chloro phenyl hydrazone (CCCP; 4 mg/kg) or vehicle (dimethyl sulfoxide). Blood pressure, heart rate (HR) and systolic function were recorded. Substrate uptake was monitored by radioactive tracers. KEY FINDINGS: Compared to the control group, the respiratory rate and body temperature increased, the left ventricle was dilated, and systolic function transiently deteriorated in the CCCP group. There was no difference in blood pressure and HR between the two groups. In cardiac substrate uptake, glucose uptake showed a 95% increase (P < 0.05), and fatty acid uptake showed a 52% decrease (P < 0.05) in CCCP-administered group. CONCLUSIONS: The deleterious effects on cardiac function and the changes in substrate uptake were observed when administered with the protonophore at a high dose.

Kyoto Congestive Heart Failure (KCHF) study: rationale and design.

AIMS: Over the last decade, major developments in medicine have led to significant changes in the clinical management of heart failure patients. This study was designed to evaluate the recent trends in clinical characteristics, management, and short-term and long-term prognosis of patients with acute decompensated heart failure (ADHF) in Japan. METHODS AND RESULTS: The Kyoto Congestive Heart Failure study is a prospective, observational, multicentre cohort study, enrolling consecutive ADHF patients from 19 participating hospitals in Japan from November 2014 to March 2016. A total of 4000 patients will be enrolled into the study and patients' anthropometric, socio-economic, and clinical data from hospital admission to discharge will be collected. In addition, in a pre-determined subgroup of patients (n=1500), a longitudinal follow-up for 2 years is scheduled. CONCLUSIONS: The Kyoto Congestive Heart Failure study will provide valuable information regarding patients with ADHF in the real-world clinical practice of Japan and will be indispensable for future clinical and policy decision-making with respect to heart failure.

The metabolic profile of a rat model of chronic kidney disease.

BACKGROUND: The kidney is always subjected to high metabolic demand. The aim of this study was to characterize metabolic profiles of a rat model of chronic kidney disease (CKD) with cardiorenal syndrome (CRS) induced by prolonged hypertension. METHODS: We used inbred male Dahl salt-sensitive (DS) rats fed an 8% NaCl diet from six weeks of age (high-salt; HS group) or a 0.3% NaCl diet as controls (low-salt; LS group). We analyzed function, pathology, metabolome, and the gene expression related to energy metabolism of the kidney. RESULTS: DS rats with a high-salt diet showed hypertension at 11 weeks of age and elevated serum levels of creatinine and blood urea nitrogen with heart failure at 21 weeks of age. The fibrotic area in the kidneys increased at 21 weeks of age. In addition, gene expression related to mitochondrial function was largely decreased. The levels of citrate and isocitrate increased and the gene expression of alpha-ketoglutaratedehydrogenase and succinyl-CoA synthetase decreased; these are enzymes that metabolize citrate and isocitrate, respectively. In addition, the levels of succinate and acetyl Co-A, both of which are metabolites of the tricarboxylic acid (TCA) cycle, decreased. CONCLUSIONS: DS rats fed a high-salt diet were deemed a suitable model of CKD with CRS. Gene expression and metabolites related to energy metabolism and mitochondria in the kidney significantly changed in DS rats with hypertension in accordance with the progression of renal injury.

Branched-chain amino acids ameliorate heart failure with cardiac cachexia in rats.

AIMS: Heart failure (HF) is associated with changes in energy metabolism of the heart, as well as in extra-cardiac organs such as the skeletal muscles. Cardiac cachexia is a common complication and is associated with poor prognosis. Branched-chain amino acids (BCAAs) reportedly improve sarcopenia and cancer cachexia. We tested the hypothesis that BCAA ameliorates HF with cardiac cachexia. MAIN METHODS: We used Dahl salt-sensitive (DS) rats fed a high-salt diet as a model of HF. DS rats fed a low-salt diet were used as a control. BCAA were administered in drinking water from 11weeks of age, when cardiac hypertrophy was established but the cardiac function was preserved. Survival and the cardiac function were monitored, and animals were sacrificed at 21weeks of age and analyzed. KEY FINDINGS: In HF rats, BCAA treatment decreased the heart rate, preserved the cardiac function, and prolonged survival. BCAA also prevented body weight loss, associated with preservation of the skeletal muscle weight. Moreover, gene expression related to mitochondrial biogenesis and function was increased with BCAA in skeletal muscles. SIGNIFICANCE: BCAA preserved the body weight and cardiac function and prolonged survival in HF rats. The expression of genes involved in mitochondrial biogenesis and function in skeletal muscles was increased by BCAA.

Measurement of technetium-99m sestamibi signals in rats administered a mitochondrial uncoupler and in a rat model of heart failure.

BACKGROUND: Many methods have been used to assess mitochondrial function. Technetium-99m sestamibi ((99m)Tc-MIBI), a lipophilic cation, is rapidly incorporated into myocardial cells by diffusion and mainly localizes to the mitochondria. The purpose of this study was to investigate whether measurement of (99m)Tc-MIBI signals in animal models could be used as a tool to quantify mitochondrial membrane potential at the organ level. METHODS AND RESULTS: We analyzed (99m)Tc-MIBI signals in Sprague-Dawley (SD) rat hearts perfused with carbonyl cyanide m-chlorophenylhydrazone (CCCP), a mitochondrial uncoupler known to reduce the mitochondrial membrane potential. (99m)Tc-MIBI signals could be used to detect changes in the mitochondrial membrane potential with sensitivity comparable to that obtained by two-photon laser microscopy with the cationic probe tetramethylrhodamine ethyl ester (TMRE). We also measured (99m)Tc-MIBI signals in the hearts of SD rats administered CCCP (4 mg/kg intraperitoneally) or vehicle. (99m)Tc-MIBI signals decreased in rat hearts administered CCCP, and the ATP content, as measured by (31)P magnetic resonance spectroscopy, decreased simultaneously. Next, we administered (99m)Tc-MIBI to Dahl salt-sensitive rats fed a high-salt diet, which leads to hypertension and heart failure. The (99m)Tc-MIBI signal per heart tissue weight was inversely correlated with heart weight, cardiac function, and the expression of atrial natriuretic factor, a marker of heart failure, and positively correlated with the accumulation of labeled fatty acid analog. The (99m)Tc-MIBI signal per liver tissue weight was lower than that per heart tissue weight. CONCLUSION: Measurement of (99m)Tc-MIBI signals can be an effective tool for semiquantitative investigation of cardiac mitochondrial membrane potential in the SD rat model by using a chemical to decrease the mitochondrial membrane potential. The (99m)Tc-MIBI signal per heart tissue weight was inversely correlated with the severity of heart failure in the Dahl rat model.

Long-term clinical outcomes after sirolimus-eluting stent implantation for unprotected left main coronary artery disease.

Previous studies reporting long-term (≥5 year) clinical outcome in patients with unprotected left main coronary artery (LMCA) disease undergoing drug-eluting stent (DES) implantation are currently limited, although late adverse events beyond 1 year are one of the major concerns of DES. We evaluated long-term clinical outcomes in 134 consecutive patients who underwent sirolimus-eluting stents (SES) for unprotected LMCA lesion in a single center from 2004 to 2009. The median follow-up duration was 3.8 (range: 0.5-7.9) years. Eight patients suffered from serious cardiovascular events potentially related to LMCA lesion (primary outcome measure) (sudden cardiac death: N = 5, emergent coronary revascularization for the LMCA lesion: N = 2, and acute congestive heart failure related to LMCA lesion: N = 1) with the cumulative 5-year incidence of only 4.4 %. The cumulative 5-year incidence of all-cause death, cardiac death, target vessel myocardial infarction, definite stent thrombosis, and target-lesion revascularization was 26.5, 8.1, 0, 0, and 12.9 %, respectively. In a subgroup analysis, the cumulative incidence of the primary outcome measure was significantly higher in patients with 2-stenting (N = 27) than in patients with 1-stenting (N = 107) (14.0 and 2.2 %, P < 0.001). All 8 patients with serious adverse events had a true bifurcation lesion and 5 patients received 2-stenting for the LMCA lesion. SES implantation in patients with unprotected LMCA lesion was associated with a favorable long-term outcome with acceptably low rate of serious adverse event potentially related to LMCA lesion. However, complex LMCA lesions necessitating 2-stenting strategy might be associated with higher risk for serious adverse events.

Enhanced cardiac Akt/protein kinase B signaling contributes to pathological cardiac hypertrophy in part by impairing mitochondrial function via transcriptional repression of mitochondrion-targeted nuclear genes.

Sustained Akt activation induces cardiac hypertrophy (LVH), which may lead to heart failure. This study tested the hypothesis that Akt activation contributes to mitochondrial dysfunction in pathological LVH. Akt activation induced LVH and progressive repression of mitochondrial fatty acid oxidation (FAO) pathways. Preventing LVH by inhibiting mTOR failed to prevent the decline in mitochondrial function, but glucose utilization was maintained. Akt activation represses expression of mitochondrial regulatory, FAO, and oxidative phosphorylation genes in vivo that correlate with the duration of Akt activation in part by reducing FOXO-mediated transcriptional activation of mitochondrion-targeted nuclear genes in concert with reduced signaling via peroxisome proliferator-activated receptor α (PPARα)/PGC-1α and other transcriptional regulators. In cultured myocytes, Akt activation disrupted mitochondrial bioenergetics, which could be partially reversed by maintaining nuclear FOXO but not by increasing PGC-1α. Thus, although short-term Akt activation may be cardioprotective during ischemia by reducing mitochondrial metabolism and increasing glycolysis, long-term Akt activation in the adult heart contributes to pathological LVH in part by reducing mitochondrial oxidative capacity.

Persistent overexpression of phosphoglycerate mutase, a glycolytic enzyme, modifies energy metabolism and reduces stress resistance of heart in mice.

BACKGROUND: Heart failure is associated with changes in cardiac energy metabolism. Glucose metabolism in particular is thought to be important in the pathogenesis of heart failure. We examined the effects of persistent overexpression of phosphoglycerate mutase 2 (Pgam2), a glycolytic enzyme, on cardiac energy metabolism and function. METHODS AND RESULTS: Transgenic mice constitutively overexpressing Pgam2 in a heart-specific manner were generated, and cardiac energy metabolism and function were analyzed. Cardiac function at rest was normal. The uptake of analogs of glucose or fatty acids and the phosphocreatine/ßATP ratio at rest were normal. A comprehensive metabolomic analysis revealed an increase in the levels of a few metabolites immediately upstream and downstream of Pgam2 in the glycolytic pathway, whereas the levels of metabolites in the initial few steps of glycolysis and lactate remained unchanged. The levels of metabolites in the tricarboxylic acid (TCA) cycle were altered. The capacity for respiration by isolated mitochondria in vitro was decreased, and that for the generation of reactive oxygen species (ROS) in vitro was increased. Impaired cardiac function was observed in response to dobutamine. Mice developed systolic dysfunction upon pressure overload. CONCLUSIONS: Constitutive overexpression of Pgam2 modified energy metabolism and reduced stress resistance of heart in mice.

Metastasis-associated protein, S100A4 mediates cardiac fibrosis potentially through the modulation of p53 in cardiac fibroblasts.

Metastasis-associated protein, S100A4 is suggested as a marker for fibrosis in several organs. It also modulates DNA binding of p53 and affects its function. However, the functional role of S100A4 in the myocardium has remained unclear. Therefore, we investigated the role of S100A4 and its relationship with p53 in cardiac fibrosis. In Dahl-rat hypertensive heart disease model, S100A4 was upregulated in the hypertrophic myocardium and further activated during transition to heart failure (HF). It was expressed in various cells including fibroblasts. In in vitro cardiac fibroblasts, the knockdown of S100A4 significantly suppressed both cell proliferation and collagen expressions. S100A4 co-localized and interacted with p53 in the nucleus. S100A4 knockdown increased the expression of p53-downstream genes, p21 and mdm2, and concomitant knockdown of p53 recovered cell proliferation and collagen expression. Transverse aortic constriction (TAC) was performed in S100A4 knockout (KO) mice, which showed a similar baseline-phenotype to wild type (WT) mice. Although there was no difference in hypertrophic response, KO mice showed reduced interstitial fibrosis, decreased myofibroblasts, and suppressed expressions of collagens and profibrotic cytokines in the left ventricle. Also, DNA microarray analysis showed that S100A4 knockout in vivo had a significant impact on expressions of p53-associated genes. These findings suggest that S100A4 modulates p53 function in fibroblasts and thereby mediates myocardial interstitial fibrosis through two distinct mechanisms; cell proliferation and collagen expression. Blockade of S100A4 may have therapeutic potential in cardiac hypertrophy and HF by attenuating cardiac fibrosis.

Percutaneous balloon valvuloplasty for bioprosthetic mitral valve stenosis.

Percutaneous transcatheter mitral valvuloplasty is the indicated treatment of choice for symptomatic native mitral valve stenosis, but there have been limited reports of successful procedures of balloon valvuloplasty for bioprosthetic mitral valve stenosis. We present the case of a 62-year-old woman suffering from progressive dyspnea due to bioprosthetic mitral valve stenosis. The measured mean pressure gradient across the mitral valve was 30 mmHg and the mitral valve area was 0.73 cm(2). Redoing mitral replacement was considered high risk and was refused by the patient. Percutaneous balloon valvuloplasty was performed with an Inoue balloon catheter inflated to 20 mm. The patient's symptoms immediately improved after the procedure, with no procedure-related complications. The mean pressure gradient across the valve decreased to 19 mmHg, and the mitral valve area increased to 1.21 cm(2) in postprocedural echocardiography. We conducted a literature search and identified 26 cases of balloon valvuloplasty for degenerated bioprosthetic valves. Of these, 14 cases were bioprosthetic mitral valves, and the results were favorable. However, more case reports are required to establish an evidence base for future expert recommendation of balloon valvuloplasty of prosthetic mitral valve. Meanwhile, balloon valvuloplasty will serve a niche role in highly selected patients with prosthetic mitral valve stenosis.

Aging as a substrate of heart failure.

Heart failure is a typical age-associated disease. However, the mechanism by which heart function declines and heart failure increases in association with age is not clear. Recent advances in basic science clarify several important mechanisms of aging. The mechanisms identified are likely to serve as substrates by which heart function declines and predisposes elderly people to heart failure. One such mechanism is insulin/insulin-like growth factor (IGF)-1 signaling. Suppression of insulin/IGF-1 signaling prevents cardiac aging associated with improved protein homeostasis in the heart. However, the role of insulin/IGF-1 signaling in heart diseases is likely to be pleiotropic, and both protective and sensitizing effects have been described in different contexts. Reduction in function of extra-cardiac organs is likely to be another important mechanism by which heart failure increases with aging, since heart failure is a multiple organ system disease.

Effects of machine-assisted cycling on exercise capacity and endothelial function in elderly patients with heart failure.

BACKGROUND: Conventional exercise training (ET) for elderly patients with heart failure (HF) includes low-intensity stretching and gait training. The effects of 2 types of low-intensity ET - machine-assisted cycling and conventional ET - on exercise capacity and endothelial function of elderly patients with HF was investigated in the present study. METHODS AND RESULTS: Twenty-seven elderly patients with HF (mean age: 79.5 years) were randomly assigned to either a machine-assisted cycling group or a conventional ET group. At baseline and after 2 weeks of ET, all patients were tested for 6-minute walk distance (6MWD) and digital reactive hyperemia-peripheral arterial tonometry (RH-PAT). After 2 weeks of ET, a significant increase in 6MWD was observed in both groups with no significant difference between the groups. RH-PAT index significantly increased in patients aged ≤80 (1.55±0.33 to 1.93±0.62, P=0.035) and a trend toward increase in RH-PAT index in the machine-assisted cycling group was observed (1.59±0.52 to 1.93±0.63, P=0.053), although no change was observed in the conventional ET group. In the multivariate model, patients' age and machine-assisted cycling were associated with the increases in RH-PAT index (P<0.05). CONCLUSIONS: Machine-assisted cycling appeared to be as effective as conventional ET on exercise capacity in elderly patients with HF. Additionally, machine-assisted cycling has the potential to improve endothelial function in these patients.

Effect of persistent activation of phosphoinositide 3-kinase on heart.

AIMS: Insulin/insulin-like growth factor-1 (IGF-1) signaling plays an important role in many biological processes. The class IA isoform of phosphoinositide 3-kinase (PI3K) is an important downstream effector of the insulin/IGF-1 signaling pathway. The aim of this study is to examine the effect of persistent activation of PI3K on gene expression and markers of cellular senescence in murine hearts. MAIN METHODS: Transgenic mice expressing a constitutively active PI3K in a heart-specific manner were analyzed at the ages of 3 and 20 months. Effects of persistent activation of PI3K on gene expression were comprehensively analyzed using microarrays. KEY FINDINGS: Upon comprehensive gene expression profiling, the genes whose expression was increased included those for several heat shock chaperons. The amount and nuclear localization of a forkhead box O (FOXO) protein was increased. In addition, the gene expression of insulin receptor substrate-2 decreased, and that of phosphatase and tensin homolog deleted on chromosome ten (PTEN) increased, suggesting that the persistent activation of PI3K modified the expression of molecules of insulin/IGF-1 signaling. The expression of markers of cellular senescence, such as senescence-associated beta-galactosidase activity, cell cycle inhibitors, proinflammatory cytokines, and lipofuscin, did not differ between old wild-type and caPI3K mice. SIGNIFICANCE: The persistent activation of PI3K modified the expression of molecules of insulin/IGF-1 signaling pathway in a transgenic mouse line. Markers of cellular senescence were not changed in the aged mutant mice.

Analysis of liver metabolism in a rat model of heart failure.

BACKGROUND: Cachexia, namely body wasting, is a common complication in cases of congestive heart failure (CHF). Although, neurohumoral and immune abnormalities are associated with the condition, precisely how the imbalance of catabolism and anabolism is responsible for the wasting process is not known. METHODS: We analyzed markers of cachexia in Dahl salt-sensitive rats which show marked hypertension with preserved systolic function at 11 weeks and CHF at 17-19 weeks of age. We also analyzed the change in hepatic metabolism associated with CHF since liver plays a central role in the systemic regulation of catabolism and anabolism. RESULTS: In CHF rats, a failure to grow was observed and blood hepatic protein levels were decreased associated with increased blood proinflammatory cytokine levels, indicating that Dahl rats serve as a model of cardiac cachexia. Food intake was reduced, and blood sugar and insulin levels were decreased. Despite the apparent fasting condition, blood fatty acid levels were decreased and triglycerides levels were increased. In CHF rats, liver incorporated more glucose, the gene expression related to gluconeogenesis was decreased, the gene expression related to lipogenesis was increased, and the triglyceride content of the liver was increased. The paradoxical production of triglycerides synthesis in fasting rats was associated with a proinflammatory response in liver. CONCLUSIONS: The Dahl salt-sensitive rat can be used as a model of cardiac cachexia. The cachexia was associated with abnormal hepatic metabolism that might work as a maladaptive response during the progression of CHF.

Constitutive SIRT1 overexpression impairs mitochondria and reduces cardiac function in mice.

Heart failure is associated with a change in cardiac energy metabolism. SIRT1 is a NAD(+)-dependent protein deacetylase, and important in the regulation of cellular energy metabolism. To examine the role of SIRT1 in cardiac energy metabolism, we created transgenic mice overexpressing SIRT1 in a cardiac-specific manner, and investigated cardiac functional reserve, energy reserve, substrate uptake, and markers of mitochondrial function. High overexpression of SIRT1 caused dilated cardiomyopathy. Moderate overexpression of SIRT1 impaired cardiac diastolic function, but did not cause heart failure. Fatty acid uptake was decreased and the number of degenerated mitochondria was increased dependent on SIRT1 gene dosage. Markers of reactive oxygen species were decreased. Changes in morphology and reactive oxygen species were associated with the reduced expression of genes related to mitochondrial function and autophagy. In addition, the respiration of isolated mitochondria was decreased. Cardiac function was normal in transgenic mice expressing a low level of SIRT1 at baseline, but the mice developed cardiac dysfunction upon pressure overload. In summary, the constitutive overexpression of SIRT1 reduced cardiac function associated with impaired mitochondria in mice.

Impact of diabetes on cardiovascular outcomes in hemodialysis patients undergoing coronary revascularization.

BACKGROUND: Among hemodialysis (HD) patients, those who have diabetes have poorer cardiovascular outcomes than non-diabetic patients, but the impact of diabetes on cardiovascular outcomes has not been fully elucidated in HD patients undergoing coronary revascularization. METHODS AND RESULTS: We identified 375 HD patients (203 diabetes, 172 non-diabetes) and 9,006 patients without HD (3,455 diabetes, 5,551 non-diabetes) in the database of the CREDO-Kyoto registry of patients undergoing their first coronary revascularization. In non-HD patients, significantly higher risks of death (10.8% vs. 7.7%, P < 0.0001; adjusted hazard ratio (HR) 1.29, P < 0.0001) and major adverse cardiovascular events (MACE), a composite of death, myocardial infarction and stroke (18.8% vs. 13.3%, P < 0.0001; HR 1.36, P < 0.0001) were seen in diabetic patients than in non-diabetic patients through 4-year follow-up. Analysis in HD patients showed that the duration of HD before first coronary revascularization was significantly shorter in diabetic patients than in non-diabetic patients (median interval: 858 vs. 2,216 days, P < 0.0001). In contrast to the results in non-HD patients, the risks of death (41.9% vs. 39.1%, P=0.75; HR 0.98, P=0.93) and MACE (45.6% vs. 45.8%, P=0.83; HR 0.87, P=0.50) after first revascularization were comparable between diabetic and non-diabetic HD patients. There were significant interactions between HD and diabetes for death and for MACE. CONCLUSIONS: HD patients who require coronary revascularization have extremely poor outcomes irrespective of concomitant diabetes.

Inter- and intra-observer variability for assessment of the synergy between percutaneous coronary intervention with TAXUS and cardiac surgery (SYNTAX) score and association of the SYNTAX score with clinical outcome in patients undergoing unprotected left main stenting in the real world.

BACKGROUND: The Synergy Between Percutaneous Coronary Intervention With TAXUS and Cardiac Surgery (SYNTAX) score was proposed as a method to evaluate the complexity of coronary anatomy. However, the reproducibility of assessment for the SYNTAX score in unprotected left main coronary artery (ULMCA) disease has not yet been adequately evaluated. The purpose of this study is to assess inter- and intra-observer variability for the assessment of the SYNTAX score in patients undergoing ULMCA stenting in daily clinical practice. METHODS AND RESULTS: The SYNTAX score of 101 consecutive patients who underwent ULMCA stenting with sirolimus-eluting stent was independently assessed by 2 experienced interventional cardiologists. One of the 2 cardiologists evaluated all the cases again 6 months after the initial assessment. The κ value for inter-observer variability in estimating the SYNTAX score was 0.62 according to the dichotomized analysis (≥ 33, < 33) and 0.58 according to the tertile analysis (< 23, 23 ≤ - < 33, ≥ 33), while the intra-observer variability was 0.78 and 0.69, respectively. Patients with a high SYNTAX score (≥ 33, n = 55) compared with those with low or intermediate score (< 33, n = 46) had a significantly higher rate of target-lesion revascularization (TLR) of the ULMCA lesion at 2 years (24% vs. 4.4%, P = 0.01). CONCLUSIONS: Both inter- and intra-observer variability for estimating the SYNTAX score were within an acceptable range and a high SYNTAX score showed a higher rate of TLR in patients undergoing ULMCA stenting in daily clinical practice.