Potential impact of carbohydrate and fat intake on pathological left ventricular hypertrophy

Metaproteomics analysis of anaerobic digestion of food waste by the addition of calcium peroxide and magnetite

Adding trace calcium peroxide and magnetite into a semi-continuous digester is a new method to effectively improve the anaerobic digestion of food waste. However, the microbial mechanism in this system has not been fully explored. Metaproteomics further revealed that the most active and significantly regulated genus u_p_Chloroflexi had formed a good cooperative relationship with Methanomicrobiales and Methanothrix in the system. u_p_Chloroflexi decomposed more organic compounds into CO2, acetate, amino acids, and other substances by alternating between short aerobic-anaerobic respiration. It perceived and adapted to the surrounding environment by producing biofilm, extracellular enzymes, and accelerating substrate transport, formed a respiratory barrier, and enhanced iron transport capacity by using highly expressed cytochrome C. The methanogens formed reactive oxygen species scavengers and reduced iron transport to prevent oxidative damage. This study provides new insight for improving the efficiency of anaerobic digestion of food waste and identifying key microorganisms and their regulated functional proteins in the calcium peroxide-magnetite digestion system.IMPORTANCEPrevious study has found that the combination of calcium peroxide and magnetite has a good promoting effect on the anaerobic digestion process of food waste. Through multiple omics approaches, information such as microbial population structure and changes in metabolites can be further analyzed. This study can help researchers gain a deeper understanding of the digestion pathway of food waste under the combined action of calcium peroxide and magnetite, further elucidate the impact mechanisms of calcium peroxide and magnetite at the microbial level, and provide theoretical guidance to improve the efficiency and stability of anaerobic digestion of food waste, as well as reduce operational costs. This research contributes to improving energy recovery efficiency, promoting sustainable management and development of food waste, and is of great significance to environmental protection.

Osthole Prevents Heart Damage Induced by Diet-Induced Metabolic Syndrome: Role of Fructokinase (KHK)

There is increasing evidence that either ingested or produced fructose may have a role in metabolic syndrome. While not commonly considered a criterion for metabolic syndrome, cardiac hypertrophy is often associated with metabolic syndrome, and its presence carries increased cardiovascular risk. Recently it has been shown that fructose and fructokinase C (KHK) can be induced in cardiac tissue. Here we tested whether diet-induced metabolic syndrome causes heart disease associated with increased fructose content and metabolism and whether it can be prevented with a fructokinase inhibitor (osthole). Male Wistar rats were provided a control diet (C) or high fat/sugar diet for 30 days (MS), with half of the latter group receiving osthol (MS+OT, 40 mg/kg/d). The Western diet increased fructose, uric acid, and triglyceride concentrations in cardiac tissue associated with cardiac hypertrophy, local hypoxia, oxidative stress, and increased activity and expression of KHK in cardiac tissue. Osthole reversed these effects. We conclude that the cardiac changes in metabolic syndrome involve increased fructose content and its metabolism and that blocking fructokinase can provide cardiac benefit through the inhibition of KHK with modulation of hypoxia, oxidative stress, hypertrophy, and fibrosis.

Hypertriglyceridemic waist phenotype is associated with left ventricular hypertrophy in Chinese hypertension patients

Left ventricular hypertrophy (LVH), the most common target organ damage in patients with hypertension, is closely related to excessive visceral adipose tissue (VAT) accumulation in the body. The hypertriglyceridemic waist (HTHW) phenotype can act as a surrogate marker of excessive VAT. However, the relationship between the HTHW phenotype and LVH in patients with hypertension remains unknown. The present study aimed to investigate whether the HTHW phenotype is associated with LVH, using echocardiography in a cross-sectional study involving 4470 middle-aged and older Chinese patients with hypertension. Logistic regression analysis revealed that patients with the HTHW phenotype were 1.52-fold more likely to experience LVH than those with normal triglyceride levels and normal waist circumference. This association was independent of age, sex, and other potentially confounding factors. In the stratified analysis, a stronger correlation was found among women, people of at least 70 years of age, and people with hyperuricemia. These results suggest that distinguishing the HTHW phenotype in patients with hypertension could serve as a simple and effective screening strategy for identifying people with a higher risk of developing LVH.

Association between triglyceride glucose index and worsening heart failure in significant secondary mitral regurgitation following percutaneous coronary intervention

BACKGROUND

The triglyceride glucose (TyG) index is an alternative to insulin resistance (IR) as an early indicator of worsening heart failure (HF). Patients with secondary mitral regurgitation (sMR) often experience progressive deterioration of cardiac function. This study aimed to investigate the relationship between the TyG index and worsening of HF in significant sMR (grade  ≥ 2) following percutaneous coronary intervention (PCI).

METHODS

This study enrolled participants with significant sMR following PCI from a multicenter cohort study. The patients were divided into the following 3 groups according to tertiles of TyG index: T1, TyG ≤ 8.51; T2, TyG > 8.51 to ≤ 8.98; and T3, TyG > 8.98. The main clinical outcome was worsening HF including unplanned rehospitalization or unscheduled physician office/emergency department visit due to HF and unplanned mitral valve surgery.

RESULTS

A total of 922 patients (mean ± SD age, 64.1 ± 11.0 years; 79.6% male) were enrolled. The incidence of worsening HF was 15.5% in T1, 15.7% in T2, and 26.4% in T3. In the multivariable model, the highest TyG tertile (T3 group) was more strongly correlated with worsening HF than the lowest tertile (T1 group) after adjusting for confounders (adjusted hazard ratio, 2.44; 95% confidence interval, 1.59-3.72; P < 0.001). The addition of TyG to risk factors such as N-terminal pro brain natriuretic peptide and clinical models improved the predictive ability of TyG for worsening HF.

CONCLUSIONS

Elevated preprocedural TyG index is a significant and independent risk factor for worsening HF in sMR following PCI that can be used for risk stratification.

Echocardiographic, morphometric and biomarker changes in female cats followed from 6 to 24 months of life

OBJECTIVES

The aim of the study was to evaluate cardiac size and early growth through echocardiographic, body weight (BW), body condition score (BCS), morphometric and biomarker changes in cats followed from 6 to 24 months of age.

METHODS

Twenty-four female European shorthair colony cats were evaluated at birth for BW and at 6, 12, 18 and 24 months of age for BW, BCS, head length (HL) and head width (HW), N-terminal pro B-type natriuretic peptide (NT-proBNP), insulin-like growth factor-1 (IGF-1) and echocardiographic measurements.

RESULTS

BCS, HW, left ventricular free wall in diastole, left atrium diameter and aortic diameter increased significantly between 6 and 12 months, while BW, HL and interventricular septum in diastole increased significantly between 6, 12 and 18 months, and BW decreased significantly between 18 and 24 months. NT-proBNP decreased significantly between 6 and 12 months. IGF-1 increased significantly between 6 and 12 months but decreased significantly between 12 and 18 months.

CONCLUSIONS AND RELEVANCE

This study prospectively evaluated changes in echocardiographic measurements, BW, BCS, HL, HW, IGF-1 and NT-proBNP in cats during the first 2 years of life. Results show a comparable change over time for different variables. These findings contribute to the understanding of a possible relationship between cardiac measures and body size from young age through to adulthood.

Association of diet with left ventricular wall thickness, troponin I and IGF-1 in cats with subclinical hypertrophic cardiomyopathy

BACKGROUND

Cats with subclinical hypertrophic cardiomyopathy (sHCM) have elevated serum insulin and serum amyloid A concentrations correlating with the degree of cardiac hypertrophy. Diet might affect these and other cardiac variables.

OBJECTIVE

Evaluate the effect of a complete, balanced diet with restricted starch and supplemented with eicosapentaenoic acid + docosahexaenoic acid (EPA + DHA) on echocardiographic variables and cardiac biomarkers in cats with sHCM.

ANIMALS

Forty-four client-owned cats with sHCM.

METHODS

A prospective, randomized, double-blind, multicenter study enrolled cats with end-diastole interventricular septum thickness (IVSd) or left ventricular wall thickness (LVWd) ≥6 mm, or both. Nonsedated, fasted cats were examined at baseline and after 6 and 12 months of Test (restricted starch and EPA + DHA supplements) (n = 23) or Control (unrestricted starch without EPA + DHA supplementation) (n = 21) diet. Assessments included auscultation, body weight, body condition score, echocardiography and blood analysis. Linear and generalized mixed models analyzed diet, time and diet * time interactions (5% significance level).

RESULTS

No differences between diet groups were significant for any variable at any timepoint. There were significant decreases in the Test but not Control group in maximum IVSd (P = .03), maximum LVWd (P = .02) and insulin-like growth factor-1 levels (P = .04) after 12 months, and in ultrasensitive cardiac troponin I (cTnI) (P = .001) after 6 months; effect sizes (95% confidence interval) were 0.53 (0.09; 0.99), 0.63 (0.18; 1.09), 0.61 (0.16; 1.07), and 0.37 (-0.06; 0.8), respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

Cats with sHCM fed Test diet had significant decreases in echocardiographic variables of sHCM and in cTnI and IGF-1.

Dietary Fat and Sugar Differentially Affect β-Adrenergic Stimulation of Cardiac ERK and AKT Pathways in C57BL/6 Male Mice Subjected to High-Calorie Feeding

BACKGROUND

High dietary fat and sugar promote cardiac hypertrophy independently from an increase in blood pressure. The respective contribution that each macronutrient exerts on cardiac growth signaling pathways remains unclear.

OBJECTIVE

The goal of this study was to investigate the mechanisms by which high amounts of dietary fat and sugar affect cardiac growth regulatory pathways.

METHODS

Male C57BL/6 mice (9 wk old; n = 20/group) were fed a standard rodent diet (STD; kcal% protein-fat-carbohydrate, 29-17-54), a high-fat diet (HFD; 20-60-20), a high-fat and high-sugar Western diet (WD; 20-45-35), a high-sugar diet with mixed carbohydrates (HCD; 20-10-70), or a high-sucrose diet (HSD; 20-10-70). Body composition was assessed weekly by EchoMRI. Whole-body glucose utilization was assessed with an intraperitoneal glucose tolerance test. After 6 wk on diets, mice were treated with saline or 20 mg/kg isoproterenol (ISO), and the activity of cardiac growth regulatory pathways was analyzed by immunoblotting. Data were analyzed by ANOVA with data from the STD group included for references only.

RESULTS

Compared with HCD and HSD, WD and HFD increased body fat mass 2.7- to 3.8-fold (P < 0.001), induced glucose intolerance (P < 0.001), and increased insulin concentrations >1.5-fold (P < 0.05), thereby enhancing basal and ISO-stimulated AKT phosphorylation at both threonine 308 and serine 473 residues (+25-63%; P < 0.05). Compared with HFD, the high-sugar diets potentiated ISO-mediated stimulation of the glucose-sensitive kinases PYK2 (>47%; P < 0.05 for HCD and HSD) and ERK (>34%; P < 0.05 for WD, HCD, and HSD), thereby leading to increased phosphorylation of protein synthesis regulator S6K1 at threonine 389 residue (>64%; P < 0.05 for WD, HCD, and HSD).

CONCLUSIONS

Dietary fat and sugar affect cardiac growth signaling pathways in C57BL/6 mice through distinct and additive mechanisms. The findings may provide new insights into the role of overnutrition in pathological cardiac remodeling.

Associations among echocardiography, cardiac biomarkers, insulin metabolism, morphology, and inflammation in cats with asymptomatic hypertrophic cardiomyopathy

Background

Insulin, insulin‐like growth factor‐1 (IGF‐1), and inflammation possibly are involved in cats with asymptomatic hypertrophic cardiomyopathy (aHCM).

Objectives

To evaluate echocardiography, morphology, cardiac and inflammatory markers, insulin and IGF‐1 in cats with aHCM.

Animals

Fifty‐one client‐owned cats with aHCM.

Methods

Observational descriptive study. Variables (body weight [BW], body condition score [BCS], echocardiography, and serum concentrations of N‐terminal pro‐B‐type natriuretic peptide [NT‐proBNP], ultra‐sensitive troponin‐I [c‐TnI], serum amyloid A [SAA], insulin, glucose and IGF‐1) were evaluated for significant increases above echocardiography cutoff values and laboratory reference ranges, associations and effect of left atrial (LA) remodeling and generalized hypertrophy.

Results

Cats with aHCM had BCS ≥6/9 (P = .01) and insulin (P < .001), NT‐proBNP (P = .001) and cTn‐I (P < .001) above laboratory reference ranges. Associations were present between NT‐proBNP and maximum end‐diastolic interventricular septum thickness (IVSd; ρ = .32; P = .05), maximum end‐diastolic left ventricular free wall thickness;(ρ = .41; P = .01), LA/Aorta (ρ = .52; P = .001) and LA diameter (LA‐max; ρ = .32; P = .05); c‐TnI and LA/Aorta (ρ = .49; P = .003) and LA‐max (ρ = .28; P = .05); and SAA and number of IVSd regions ≥6 mm thickness (ρ = .28; P = .05). Body weight and BCS were associated with IGF‐1 (r = 0.44; P = .001), and insulin (ρ = .33; P = .02), glucose (ρ = .29; P = .04) and IGF‐1 (ρ = .32; P = .02), respectively. Concentrations of NT‐proBNP (P = .02) and c‐TnI (P = .01), and SAA (P = .02), were higher in cats with LA remodeling, and generalized hypertrophy, respectively.

Conclusions and clinical importance

Results suggest potential implications of insulin, IGF‐1, and inflammation in cats with aHCM, but it remains to be confirmed whether these findings represent a physiological process or a part of the pathogenesis and development of disease.

Hypercaloric diet models do not develop heart failure, but the excess sucrose promotes contractility dysfunction

Several diseases are associated with excess of adipose tissue, and obesity is considered an independent risk factor for the development of cardiac remodeling and heart failure. Dietary aspects have been studied to elucidate the mechanisms involved in these processes. Thus, the purpose was the development and characterization of an obesity experimental model from hypercaloric diets, which resulted in cardiac remodeling and predisposition to heart failure. Thirty- day-old male Wistar rats (n = 52) were randomized into four groups: control (C), high sucrose (HS), high-fat (HF) and high-fat and sucrose (HFHS) for 20 weeks. General characteristics, comorbidities, weights of the heart, left (LV) and right ventricles, atrium, and relationships with the tibia length were evaluated. The LV myocyte cross sectional area and fraction of interstitial collagen were assayed. Cardiac function was determined by hemodynamic analysis and the contractility by cardiomyocyte contractile function. Heart failure was analyzed by pulmonary congestion, right ventricular hypertrophy, and hemodynamic parameters. HF and HFHS models led to obesity by increase in adiposity index (C = 8.3 ± 0.2% vs. HF = 10.9 ± 0.5%, HFHS = 10.2 ± 0.3%). There was no change in the morphological parameters and heart failure signals. HF and HFHS caused a reduction in times to 50% relaxation without cardiomyocyte contractile damage. The HS model presented cardiomyocyte contractile dysfunction visualized by lower shortening (C: 8.34 ± 0.32% vs. HS: 6.91 ± 0.28), as well as the Ca2+ transient amplitude was also increased when compared to HFHS. In conclusion, the experimental diets based on high amounts of sugar, lard or a combination of both did not promote cardiac remodeling with predisposition to heart failure under conditions of obesity or excess sucrose. Nevertheless, excess sucrose causes cardiomyocyte contractility dysfunction associated with alterations in the myocyte sensitivity to intracellular Ca2+.

Postprandial Vascular Dysfunction Is Associated With Raised Blood Pressure and Adverse Left Ventricular Remodeling in Adolescent Adiposity

BACKGROUND

Left ventricular hypertrophy (LVH) is a major risk factor for cardiovascular disease, including heart failure. Although linked to obesity and hypertension, its pathogenesis is multifactorial. Blunted postprandial sympathetic regulation of gut blood flow has been observed in overweight animals and suggested as a promotor of hypertension and LVH. We hypothesized that blunted postprandial superior mesenteric blood flow responses would be more common in overweight humans and associated with increased blood pressure and LVH.

METHODS

Left ventricular dimensions and hemodynamic responses to a standardized high-calorie liquid meal were measured in healthy adolescents (n=82; 39 overweight/obese) by magnetic resonance imaging. Covariates such as body mass index, blood pressure, Tanner score, and an index of insulin resistance were included in multiple regression models to examine the independent associations of mesenteric flow response with blood pressure status and LVH.

RESULTS

Food ingestion increased cardiac output (Δmean, 0.45 [SD, 0.62] L·min^-1; P=3.8×10^-8) and superior mesenteric artery flow (Δmean, 0.76 [SD, 0.35] L·min^-1; P=4.2×10^-31). A blunted mesenteric flow response was associated with increased left ventricular mass (B=-12.7 g·m^-2.7 per L·min^-1·m^-0.92; P=6×10^-5) and concentric LVH (log likelihood, -9.9; P=0.001), independently of known determinants of LVH, including body mass index. It was also associated with elevated systolic blood pressure (B=-18.0 mm Hg per L·min^-1·m^-0.92; P=0.001), but this link did not explain the association with left ventricular mass.

CONCLUSIONS

Postprandial mesenteric vascular dysfunction is associated with LVH and hypertension, independently of common risk factors for those conditions. These findings highlight a new, independent marker of cardiovascular risk in the young.

Trolox prevents high glucose-induced apoptosis in rat myocardial H9c2 cells by regulating GLUT-4 and antioxidant defense mechanism

Redox imbalance due to hyperglycemia is a causative factor for an increased generation of reactive oxygen species (ROS) that leads to mitochondrial dysfunction and the release of cytochrome-c. The aim of the present study is to elucidate the functional role of oxidative stress (OS) in the induction of apoptosis in H9c2 cells in the hyperglycemic state through glucose transporter-4 (GLUT-4) regulation and antioxidant status. H9c2 cells were incubated with 15, 24, and 33 mM glucose for 24, 48, and 72 hr to induce hyperglycemic stress. Hyperglycemic episodes have significantly influenced GLUT-4 mRNA regulation, depleted glutathione (GSH) and its associated enzymes, reduced cellular antioxidant enzymes (AOEs), caused nuclear condensation, and induced apoptosis by activating caspase-9 and 3 and annexin V binding in a concentration and duration-dependent manner. Trolox pretreatment significantly enhanced the GLUT-4 mRNA and antioxidant defense mechanism, suppressed nuclear condensation, and prevented cytochrome-c release, thereby reducing mitochondrial-dependent apoptosis. The present study shows that the toxic effect of high glucose is significantly regulated and that OS induction can be prevented through a water-soluble vitamin E analog "Trolox" treatment.

High calories but not fat content of lard-based diet contribute to impaired mitochondrial oxidative phosphorylation in C57BL/6J mice heart

Purpose

High calorie intake leads to obesity, a global socio-economic and health problem, reaching epidemic proportion in children and adolescents. Saturated and monounsaturated fatty acids from animal (lard) fat are major components of the western-pattern diet and its regular consumption leads to obesity, a risk factor for cardiovascular disease. However, no clear evidence exists whether consumption of diet rich in saturated (SFAs) and monounsaturated (MUFAs) fatty acids has detrimental effects on cardiac structure and energetics primarily due to excessive calories. We, therefore, sought to determine the impact of high calories versus fat content in diet on cardiac structure and mitochondrial energetics.

Methods

Six-week-old C57BL/6J mice were fed with high calorie, high lard fat-based diet (60% fat, HFD), high-calorie and low lard fat-based diet (10% fat, LFD), and lower-calorie and fat diet (standard chow, 12% fat, SCD) for 10 weeks.

Results

The HFD- and LFD-fed mice had higher body weight, ventricular mass and thickness of posterior and septal wall with increased cardiomyocytes diameter compared to the SCD-fed mice. These changes were associated with a reduction in the mitochondrial oxidative phosphorylation (OXPHOS) complexes I and III activity compared to the SCD-fed mice without significant differences between the HFD- and LFD-fed animals. The HFD-fed animals had higher level of malondialdehyde (MDA) than LFD and SCD-fed mice.

Conclusions

We assume that changes in cardiac morphology and selective reduction of the OXPHOS complexes activity observed in the HFD- and LFD-fed mice might be related to excessive calories with additional effect of fat content on oxidative stress.

Cardiac function and intracellular Ca2+ handling proteins are not impaired by high-saturated-fat diet-induced obesity

Obesity is often associated with changes in cardiac function; however, the mechanisms responsible for functional abnormalities have not yet been fully clarified. Considering the lack of information regarding high-saturated-fat diet-induced obesity, heart function, and the proteins involved in myocardial calcium (Ca²⁺) handling, the aim of this study was to test the hypothesis that this dietary model of obesity leads to cardiac dysfunction resulting from alterations in the regulatory proteins of intracellular Ca²⁺ homeostasis. Male Wistar rats were distributed into two groups: control (C, n=18; standard diet) and obese (Ob, n=19; high-saturated-fat diet), which were fed for 33 weeks. Cardiac structure and function were evaluated using echocardiographic and isolated papillary muscle analyses. Myocardial protein expressions of sarcoplasmic reticulum Ca²⁺-ATPase, phospholamban (PLB), PLB serine-16 phosphorylation, PLB threonine-17 phosphorylation, ryanodine receptor, calsequestrin, Na⁺/Ca²⁺ exchanger, and L-type Ca²⁺ channel were assessed by western blot. Obese rats presented 104% increase in the adiposity index (C: 4.5±1.4 vs Ob: 9.2±1.5%) and obesity-related comorbidities compared to control rats. The left atrium diameter (C: 5.0±0.4 vs Ob: 5.5±0.5 mm) and posterior wall shortening velocity (C: 36.7±3.4 vs Ob: 41.8±3.8 mm/s) were higher in the obese group than in the control. The papillary muscle function was similar between the groups at baseline and after inotropic and lusitropic maneuvers. Obesity did not lead to changes in myocardial Ca²⁺ handling proteins expression. In conclusion, the hypothesis was not confirmed, since the high-saturated-fat diet-induced obese rats did not present cardiac dysfunction or impaired intracellular Ca²⁺ handling proteins.

Possibility of a New Therapeutic Strategy for Left Ventricular Dysfunction in Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) substantially increases the risk of cardiovascular events, including heart failure (HF), due to complications such as hypertension, obesity and dyslipidemia based on metabolic syndrome, which plays the central pathological role in HF. A reason is that T2DM causes left ventricular (LV) diastolic dysfunction beginning in the early phase of the disease, which in turn increases the risk of development of HF independently of the control of blood glucose levels, blood pressure or the presence of coronary artery diseases. Intracellular metabolic disorders and increased oxidative stress due to hyperglycemia, increased insulin resistance and chronic inflammation are pathogenic mechanisms involved in the LV diastolic dysfunction caused by T2DM. These mechanisms lead to structural changes in the heart such as LV hypertrophy and interstitial fibrosis, resulting in HF. The prevalence of HF with preserved ejection fraction (HFpEF), the major pathology of LV diastolic dysfunction, has been increasing recently, and a high incidence of HFpEF in patients with T2DM was reported. An effective therapy has not been established for HFpEF because multiple comorbidities such as advanced age, hypertension, obesity, dyslipidemia, chronic kidney disease and atrial fibrillation as well as diabetes are involved in its pathology. In the present review, we review the involvement of associated conditions such as hypertension, obesity and advanced age from the aspect of the T2DM and LV diastolic dysfunction and discuss the possibility of the development of a new therapeutic strategy for LV diastolic dysfunction and HFpEF.

Transcriptional Effects of E3 Ligase Nrdp1 on Hypertrophy in Neonatal Rat Cardiomyocytes by Microarray and Integrated Gene Network Analysis

Objective: Neuregulin receptor degradation protein-1 (Nrdp1) is a novel E3 ubiquitin ligase, and we have previously shown that overexpression of Nrdp1 increased cardiomyocyte injury. However, the role of Nrdp1 in myocardial hypertrophy is unclear. In the present study, we clarified the molecular mechanisms of angiotensin II (Ang II)-induced cardiomyocyte hypertrophy regulated by Nrdp1 based on genome-wide transcriptional analysis. Methods: Neonatal rat cardiomyocytes were infected with adenoviruses containing green fluorescent protein (Ad-GFP) or wild-type Nrdp1 (Ad-Nrdp1), and then treated with Ang II for 36 h. Detection of differentially expressed genes was achieved with an Affymetrix Rat Gene 2.0 Array and Cluster and Java TreeView software. Results and Conclusion: Microarray data analysis demonstrated that Nrdp1 overexpression affected the expression of 12,140 mRNA genes in Ang II-induced cardiomyocyte hypertrophy, including the upregulation of 12,044 and the downregulation of 96. Gene ontology and globe signal transduction network analysis showed that Nrdp1 affected the expression of many genes related to stimulus response, the cell receptor pathway, and cell growth. Pathway network analysis identified myocardial metabolism, DNA replication, and the cell cycle as the most important pathways targeted by Nrdp1. lncRNA-mRNA coexpression network analysis showed that two core lncRNAs, NONRATT057160 and NONRATT054243, were involved in cardiomyotrophy regulated by Nrdp1 in cardiomyocytes. Taken together, these data provide compelling clues for further exploration of the function of Nrdp1 in heart disease.

MicroRNA Expression Signature Is Altered in the Cardiac Remodeling Induced by High Fat Diets

Recent studies have revealed the involvement of microRNAs (miRNAs) in the control of cardiac hypertrophy and myocardial function. In addition, several reports have demonstrated that high fat (HF) diet induces cardiac hypertrophy and remodeling. In the current study, we investigated the effect of diets containing different percentages of fat on the cardiac miRNA expression signature. To address this question, male C57Bl/6 mice were fed with a low fat (LF) diet or two HF diets, containing 45 kcal% fat (HF45%) and 60 kcal% fat (HF60%) for 10 and 20 weeks. HF60% diet promoted an increase on body weight, fasting glycemia, insulin, leptin, total cholesterol, triglycerides, and induced glucose intolerance. HF feeding promoted cardiac remodeling, as evidenced by increased cardiomyocyte transverse diameter and interstitial fibrosis. RNA sequencing analysis demonstrated that HF feeding induced distinct miRNA expression patterns in the heart. HF45% diet for 10 and 20 weeks changed the abundance of 64 and 26 miRNAs in the heart, respectively. On the other hand, HF60% diet for 10 and 20 weeks altered the abundance of 27 and 88 miRNAs in the heart, respectively. Bioinformatics analysis indicated that insulin signaling pathway was overrepresented in response to HF diet. An inverse correlation was observed between cardiac levels of GLUT4 and miRNA-29c. Similarly, we found an inverse correlation between expression of GSK3β and the expression of miRNA-21a-3p, miRNA-29c-3p, miRNA-144-3p, and miRNA-195a-3p. In addition, miRNA-1 overexpression prevented cardiomyocyte hypertrophy. Taken together, our results revealed differentially expressed miRNA signatures in the heart in response to different HF diets. J. Cell. Physiol. 231: 1771-1783, 2016. © 2015 Wiley Periodicals, Inc.

High-fat Diet Promotes Cardiac Remodeling in an Experimental Model of Obesity

BACKGROUND

Although nutritional, metabolic and cardiovascular abnormalities are commonly seen in experimental studies of obesity, it is uncertain whether these effects result from the treatment or from body adiposity.

OBJECTIVE

To evaluate the influence of treatment and body composition on metabolic and cardiovascular aspects in rats receiving high saturated fat diet.

METHODS

Sixteen Wistar rats were used, distributed into two groups, the control (C) group, treated with isocaloric diet (2.93 kcal/g) and an obese (OB) group, treated with high-fat diet (3.64 kcal/g). The study period was 20 weeks. Analyses of nutritional behavior, body composition, glycemia, cholesterolemia, lipemia, systolic arterial pressure, echocardiography, and cardiac histology were performed.

RESULTS

High-fat diet associates with manifestations of obesity, accompanied by changes in glycemia, cardiomyocyte hypertrophy, and myocardial interstitial fibrosis. After adjusting for adiposity, the metabolic effects were normalized, whereas differences in morphometric changes between groups were maintained.

CONCLUSION

It was concluded that adiposity body composition has a stronger association with metabolic disturbances in obese rodents, whereas the high-fat dietary intervention is found to be more related to cardiac morphological changes in experimental models of diet-induced obesity.

Moderate intensity physical activity prevents increased blood glucose concentrations, fat pad deposition and cardiac action potential prolongation following diet-induced obesity in a juvenile-adolescent rat model

Background

Both obesity and a lack of physical activity have been associated with an elevated risk of cardiovascular disease (CVD). The incidence of obesity is increasing, especially in juvenile-adolescents. While there is limited research examining the chronic effects of obesity in adolescent humans and animal models of this condition, little is also known concerning how moderate physical activity might prevent or attenuate secondary cardiovascular complications induced by obesity during adolescence. We investigated the effects of diet-induced obesity (consisting of a high-fat, high-carbohydrate diet (HFHC)) on biometric indices, vascular and airway function, cardiovascular function, systemic oxidative stress and markers of inflammation in a juvenile-adolescent rodent model. Four groups were used: control (CON), physical activity (PA) treated, HFHC and HFHC + PA (n = 16 per group). HFHC feeding started at 4 weeks of age for a period of 12 weeks. Physical activity treatment was initiated (PA and HFHC + PA groups) when the animals were 8 weeks of age, for 8 weeks.

Results

Physical activity in juvenile-adolescent healthy rats showed no change in comparison to the CON group in all experimental parameters except for increases in lipid peroxidation, decreases in inflammatory cytokines, improvements in vascular reactivity and decreased atrial responses to positive chronotropic agents. The HFHC animals were mildly hyperglycemic, hypertensive, displayed renal hypertrophy and showed increased retroperitoneal fat pad deposition compared to the CON group. HFHC + PA rats were also hypertensive, however showed improvements in cardiac electrophysiology, body weight, fat pad deposition and inflammatory signaling, in comparison to the HFHC fed rats and CON animals.

Conclusion

In conclusion, in a juvenile-adolescent animal model of diet-induced obesity engagement in physical activity is beneficial in reducing the inflammatory effects of obesity.

Insulin resistance and subclinical abnormalities of global and regional left ventricular function in patients with aortic valve sclerosis

Background

Insulin resistance, as a key mediator of metabolic syndrome, is thought to be associated with pathogenesis of calcific aortic valve disease and altered left ventricular (LV) function and structure. However, in patients with aortic valve sclerosis (AVS), the association between insulin resistance and subclinical impairment of LV function is not fully elucidated.

Methods

We studied 57 patients (mean age 70 ± 8 years, 22 women) with asymptomatic AVS but normal LV ejection fraction in echocardiography. LV longitudinal and circumferential strain and strain rate was analyzed using two-dimensional speckle tracking echocardiography. Patients with uncontrolled hypertension and diabetes mellitus, chronic kidney disease, and concomitant coronary artery disease were excluded. They were divided into the insulin-resistant group (AVS+IR; N = 28) and no insulin-resistant group (AVS-IR; N = 29) according to the median value of homeostatic model assessment index. Computed tomography scans were also performed to measure the aortic valve calcium score and the visceral adipose tissue (VAT) area. In addition, age- and sex- adjusted 28 control subjects were recruited for the comparison.

Results

There were no significant differences in LV ejection fraction or mass index among the groups. The AVS+IR group had a higher aortic valve calcium score (median 94 versus 21, P = 0.022) and a larger VAT area (113 ± 42 cm² versus 77 ± 38 cm², P = 0.001) than the AVS-IR group. Notably, LV global longitudinal strain, strain rate (SR), and early diastolic SR were significantly lower in the AVS+IR group than in the AVS-IR group and in control subjects (strain: -16.2 ± 1.6% versus -17.2 ± 1.2% and -18.9 ± 0.8%; SR: -1.18 ± 0.26 s^-1 versus -1.32 ± 0.21 s^-1 and -1.52 ± 0.08 s^-1; early diastolic SR: -1.09 ± 0.23 s^-1 versus -1.23 ± 0.18 s^-1 and -1.35 ± 0.12 s^-1; P < 0.05 for all comparison), whereas circumferential function were not significantly different. Multiple linear regression analyses revealed insulin resistance as an independent determinant of LV longitudinal strain (P = 0.017), SR (P = 0.047), and early diastolic SR (P = 0.049) regardless of LV mass index or VAT area.

Conclusions

Insulin resistance is a powerful independent predictor of subclinical LV dysfunction regardless of concomitant visceral obesity and LV hypertrophy. Thus, it may be a novel therapeutic target to prevent subsequent heart failure in patients with AVS.

The detrimental effects of acute hyperglycemia on myocardial glucose uptake

AIMS

Although acute hyperglycemic (AHG) episodes are linked to lower glucose uptake, underlying mechanisms remain unclear. We hypothesized that AHG triggers reactive oxygen species (ROS) production and increases non-oxidative glucose pathway (NOGP) activation, i.e. stimulation of advanced glycation end products (AGE), polyol pathway (PP), hexosamine biosynthetic pathway (HBP), PKC; thereby decreasing cardiac glucose uptake.

MAIN METHODS

H9c2 cardiomyoblasts were exposed to 25 mM glucose for 24h vs. 5.5mM controls ± modulating agents during the last hour of glucose exposure: a) antioxidant #1 for mitochondrial ROS (250 μM 4-OHCA), b) antioxidant #2 for NADPH oxidase-generated ROS (100 μM DPI), c) NOGP inhibitors - 100 μM aminoguanidine (AGE), 5 μM chelerythrine (PKC); 40 μM DON (HBP); and 10 μM zopolrestat (PP). ROS levels (mitochondrial, intracellular) and glucose uptake were evaluated by flow cytometry.

KEY FINDINGS

AHG elevated ROS, activated NOGPs and blunted glucose uptake. Transketolase activity (pentose phosphate pathway [PPP] marker) did not change. Respective 4-OHCA and DPI treatment blunted ROS production, diminished NOGP activation and normalized glucose uptake. NOGP inhibitory studies identified PKCβII as a key downstream player in lowering insulin-mediated glucose uptake. When we employed an agent (benfotiamine) known to shunt flux away from NOGPs (into PPP), it decreased ROS generation and NOGP activation, and restored glucose uptake under AHG conditions.

SIGNIFICANCE

This study demonstrates that AHG elicits maladaptive events that function in tandem to reduce glucose uptake, and that antioxidant treatment and/or attenuation of NOGP activation (PKC, polyol pathway) may limit the onset of insulin resistance.

Cardiac insulin-resistance and decreased mitochondrial energy production precede the development of systolic heart failure after pressure-overload hypertrophy

BACKGROUND

Cardiac hypertrophy is accompanied by significant alterations in energy metabolism. Whether these changes in energy metabolism precede and contribute to the development of heart failure in the hypertrophied heart is not clear.

METHODS AND RESULTS

Mice were subjected to cardiac hypertrophy secondary to pressure-overload as a result of an abdominal aortic constriction (AAC). The rates of energy substrate metabolism were assessed in isolated working hearts obtained 1, 2, and 3 weeks after AAC. Mice subjected to AAC demonstrated a progressive development of cardiac hypertrophy. In vivo assessment of cardiac function (via echocardiography) demonstrated diastolic dysfunction by 2 weeks (20% increase in E/E'), and systolic dysfunction by 3 weeks (16% decrease in % ejection fraction). Marked cardiac insulin-resistance by 2 weeks post-AAC was evidenced by a significant decrease in insulin-stimulated rates of glycolysis and glucose oxidation, and plasma membrane translocation of glucose transporter 4. Overall ATP production rates were decreased at 2 and 3 weeks post-AAC (by 37% and 47%, respectively) because of a reduction in mitochondrial oxidation of glucose, lactate, and fatty acids that was not accompanied by an increase in myocardial glycolysis rates. Reduced mitochondrial complex V activity was evident at 3 weeks post-AAC, concomitant with a reduction in the ratio of phosphocreatine to ATP.

CONCLUSIONS

The development of cardiac insulin-resistance and decreased mitochondrial oxidative metabolism are early metabolic changes in the development of cardiac hypertrophy, which create an energy deficit that may contribute to the progression from hypertrophy to heart failure.

Extensive impact of saturated fatty acids on metabolic and cardiovascular profile in rats with diet-induced obesity: a canonical analysis

Background

Although hypercaloric interventions are associated with nutritional, endocrine, metabolic, and cardiovascular disorders in obesity experiments, a rational distinction between the effects of excess adiposity and the individual roles of dietary macronutrients in relation to these disturbances has not previously been studied. This investigation analyzed the correlation between ingested macronutrients (including sucrose and saturated and unsaturated fatty acids) plus body adiposity and metabolic, hormonal, and cardiovascular effects in rats with diet-induced obesity.

Methods

Normotensive Wistar-Kyoto rats were submitted to Control (CD; 3.2 Kcal/g) and Hypercaloric (HD; 4.6 Kcal/g) diets for 20 weeks followed by nutritional evaluation involving body weight and adiposity measurement. Metabolic and hormonal parameters included glycemia, insulin, insulin resistance, and leptin. Cardiovascular analysis included systolic blood pressure profile, echocardiography, morphometric study of myocardial morphology, and myosin heavy chain (MHC) protein expression. Canonical correlation analysis was used to evaluate the relationships between dietary macronutrients plus adiposity and metabolic, hormonal, and cardiovascular parameters.

Results

Although final group body weights did not differ, HD presented higher adiposity than CD. Diet induced hyperglycemia while insulin and leptin levels remained unchanged. In a cardiovascular context, systolic blood pressure increased with time only in HD. Additionally, in vivo echocardiography revealed cardiac hypertrophy and improved systolic performance in HD compared to CD; and while cardiomyocyte size was unchanged by diet, nuclear volume and collagen interstitial fraction both increased in HD. Also HD exhibited higher relative β-MHC content and β/α-MHC ratio than their Control counterparts. Importantly, body adiposity was weakly associated with cardiovascular effects, as saturated fatty acid intake was directly associated with most cardiac remodeling measurements while unsaturated lipid consumption was inversely correlated with these effects.

Conclusion

Hypercaloric diet was associated with glycemic metabolism and systolic blood pressure disorders and cardiac remodeling. These effects directly and inversely correlated with saturated and unsaturated lipid consumption, respectively.

Cardiac remodeling induced by 13-cis retinoic acid treatment in acne patients

BACKGROUND

Currently, 13-cis-retinoic acid (13-cis-RA) is the most effective therapy for acne. Isotretinoin, a first-generation synthetic 13-cis-RA compound, is associated with numerous adverse effects. To investigate the cardiac effects of 13-cis-RA, acne patients receiving 13-cis-RA were studied.

METHODS

Twenty male patients with acne were enrolled in the study. Patients were treated with a dose of 0.5 mg/kg/d of isotretinoin. All participants were assessed prior to treatment and after 10 weeks of therapy with Doppler-echocardiogram.

RESULTS

Patients showed reductions in right atrium vertical diameter, left atrium longitudinal diameter, left atrium volume and left ventricular diastolic diameter over the course of treatment. Significant increases in interventricular septum diastolic thickness, posterior wall diastolic thickness, relative wall relative thickness and left ventricle (LV) mass were observed. The LV mass index showed an increase in ventricular mass and a decrease in the cavity size. Examining LV systolic function, a decrease was observed for the cardiac index.

CONCLUSION

In this study, 10 weeks of 13-cis-RA therapy at a dose of 0.5 mg/kg/d was found to promote concentric-type heart remodeling due to the occurrence of two associated events: heart hypertrophy and hypovolemia.

Effects of insulin therapy on myocardial lipid content and cardiac geometry in patients with type-2 diabetes mellitus

Aims/Hypothesis

Recent evidence suggests a link between myocardial steatosis and diabetic cardiomyopathy. Insulin, as a lipogenic and growth-promoting hormone, might stimulate intramyocardial lipid (MYCL) deposition and hypertrophy. Therefore, the aim of the present study was to investigate the short-term effects of insulin therapy (IT) on myocardial lipid content and morphology in patients with T2DM.

Methods

Eighteen patients with T2DM were recruited (age 56±2 years; HbA1c: 10.5±0.4%). In 10 patients with insufficient glucose control under oral medication IT was initiated due to secondary failure of oral glucose lowering therapy (IT-group), while 8 individuals did not require additional insulin substitution (OT-group). In order to assess MYCL and intrahepatic lipid (IHLC) content as well as cardiac geometry and function magnetic resonance spectroscopy (MRS) and imaging (MRI) examinations were performed at baseline (IT and OT) and 10 days after initiation of IT. Follow up measurements took place 181±49 days after IT.

Results

Interestingly, basal MYCLs were 50% lower in IT- compared to OT-group (0.41±0.12 vs. 0.80±0.11% of water signal; p = 0.034). After 10 days of IT, an acute 80%-rise in MYCL (p = 0.008) was observed, while IHLC did not change. Likewise, myocardial mass (+13%; p = 0.004), wall thickness in end-diastole (+13%; p = 0.030) and concentricity, an index of cardiac remodeling, increased (+28%; p = 0.026). In the long-term MYCL returned to baseline, while IHCL significantly decreased (−31%; p = 0.000). No acute changes in systolic left ventricular function were observed.

Conclusions/Interpretation

The initiation of IT in patients with T2DM was followed by an acute rise in MYCL concentration and myocardial mass.

Dietary fat and heart failure: moving from lipotoxicity to lipoprotection

There is growing evidence suggesting that dietary fat intake affects the development and progression of heart failure. Studies in rodents show that in the absence of obesity, replacing refined carbohydrate with fat can attenuate or prevent ventricular expansion and contractile dysfunction in response to hypertension, infarction, or genetic cardiomyopathy. Relatively low intake of n-3 polyunsaturated fatty acids from marine sources alters cardiac membrane phospholipid fatty acid composition, decreases the onset of new heart failure, and slows the progression of established heart failure. This effect is associated with decreased inflammation and improved resistance to mitochondrial permeability transition. High intake of saturated, monounsaturated, or n-6 polyunsaturated fatty acids has also shown beneficial effects in rodent studies. The underlying mechanisms are complex, and a more thorough understanding is needed of the effects on cardiac phospholipids, lipid metabolites, and metabolic flux in the normal and failing heart. In summary, manipulation of dietary fat intake shows promise in the prevention and treatment of heart failure. Clinical studies generally support high intake of n-3 polyunsaturated fatty acids from marine sources to prevent and treat heart failure. Additional clinical and animals studies are needed to determine the optimal diet in terms of saturated, monounsaturated, and n-6 polyunsaturated fatty acids intake for this vulnerable patient population.

Animal models for the study of arterial hypertension

Hypertension is one of the leading causes of disability or death due to stroke, heart attack and kidney failure. Because the etiology of essential hypertension is not known and may be multifactorial, the use of experimental animal models has provided valuable information regarding many aspects of the disease, which include etiology, pathophysiology, complications and treatment. The models of hypertension are various, and in this review, we provide a brief overview of the most widely used animal models, their features and their importance.

p53-induced adipose tissue inflammation is critically involved in the development of insulin resistance in heart failure

Several clinical studies have shown that insulin resistance is prevalent among patients with heart failure, but the underlying mechanisms have not been fully elucidated. Here, we report a mechanism of insulin resistance associated with heart failure that involves upregulation of p53 in adipose tissue. We found that pressure overload markedly upregulated p53 expression in adipose tissue along with an increase of adipose tissue inflammation. Chronic pressure overload accelerated lipolysis in adipose tissue. In the presence of pressure overload, inhibition of lipolysis by sympathetic denervation significantly downregulated adipose p53 expression and inflammation, thereby improving insulin resistance. Likewise, disruption of p53 activation in adipose tissue attenuated inflammation and improved insulin resistance but also ameliorated cardiac dysfunction induced by chronic pressure overload. These results indicate that chronic pressure overload upregulates adipose tissue p53 by promoting lipolysis via the sympathetic nervous system, leading to an inflammatory response of adipose tissue and insulin resistance.

Changes in myofilament proteins, but not Ca²⁺ regulation, are associated with a high-fat diet-induced improvement in contractile function in heart failure

Pathological conditions such as diabetes, insulin resistance, and obesity are characterized by elevated plasma and myocardial lipid levels and have been reported to exacerbate the progression of heart failure (HF). Alterations in cardiomyocyte Ca(2+) regulatory properties and myofilament proteins have also been implicated in contractile dysfunction in HF. However, our prior studies reported that high saturated fat (SAT) feeding improves in vivo myocardial contractile function, thereby exerting a cardioprotective effect in HF. Therefore, we hypothesized that SAT feeding improves contractile function by altering Ca(2+) regulatory properties and myofilament protein expression in HF. Male Wistar rats underwent coronary artery ligation (HF) or sham surgery (SH) and were fed normal chow (SHNC and HFNC groups) or a SAT diet (SHSAT and HFSAT groups) for 8 wk. Contractile properties were measured in vivo [echocardiography and left ventricular (LV) cannulation] and in isolated LV cardiomyocytes. In vivo measures of contractility (peak LV +dP/dt and -dP/dt) were depressed in the HFNC versus SHNC group but improved in the HFSAT group. Isolated cardiomyocytes from both HF groups were hypertrophied and had decreased percent cell shortening and a prolonged time to half-decay of the Ca(2+) transient versus the SH group; however, SAT feeding reduced in vivo myocyte hypertrophy in the HFSAT group only. The peak velocity of cell shortening was reduced in the HFNC group but not the HFSAT group and was positively correlated with in vivo contractile function (peak LV +dP/dt). The HFNC group demonstrated a myosin heavy chain (MHC) isoform switch from fast MHC-α to slow MHC-β, which was prevented in the HFSAT group. Alterations in Ca(2+) transients, L-type Ca(2+) currents, and protein expression of sarco(endo)plasmic reticulum Ca(2+)-ATPase and phosphorylated phospholamban could not account for the changes in the in vivo contractile properties. In conclusion, the cardioprotective effects associated with SAT feeding in HF may occur at the level of the isolated cardiomyocyte, specifically involving changes in myofilament function but not sarcoplasmic reticulum Ca(2+) regulatory properties.

Influence of AIN-93 diet on mortality and cardiac remodeling after myocardial infarction in rats

BACKGROUND

The AIN-93 diet was proposed by the American Institute of Nutrition with the objective of standardising studies in experimental nutrition. Our objective was to analyze the effects of AIN-93 diet after myocardial infarction in rats.

METHODS

Post weaning, the animals were divided into two groups: control (C, n=62), fed the standard diet of our laboratory (Labina); AIN-93 Group (n=70), fed the AIN-93 diet. Achieving 250 g, the animals were subjected to myocardial infarction.

RESULTS

Early mortality was increased in AIN-93 animals, associated with lower serum levels of calcium, magnesium, potassium, sodium, and phosphorus. On the other hand, after 90 days, AIN-93 showed smaller normalized left ventricular dimensions. The caloric and carbohydrate intake was smaller, but the fat intake was higher in AIN-93 rats. AIN-93 group also showed increased levels of β-hydroxyacylcoenzyme A dehydrogenase and citrate synthase. In addition, serum levels of insulin and cardiac levels of malondialdehyde, metalloproteinases-2 and -9, and TNF-α and IFN-γ were decreased in the AIN-93 group.

CONCLUSION

AIN-93 diet increased early mortality, while attenuated the chronic remodeling process after experimental coronary occlusion. Therefore, this diet has biological effects and should be use with attention in this model.

A high-fructose diet worsens eccentric left ventricular hypertrophy in experimental volume overload

The development of left ventricular (LV) hypertrophy (LVH) can be affected by diet manipulation. Concentric LVH resulting from pressure overload can be worsened by feeding rats with a high-fructose diet. Eccentric LVH is a different type of hypertrophy and is associated with volume overload (VO) diseases. The impact of an abnormal diet on the development of eccentric LVH and on ventricular function in chronic VO is unknown. This study therefore examined the effects of a fructose-rich diet on LV eccentric hypertrophy, ventricular function, and myocardial metabolic enzymes in rats with chronic VO caused by severe aortic valve regurgitation (AR). Wistar rats were divided in four groups: sham-operated on control diet (SC; n = 13) or fructose-rich diet (SF; n = 13) and severe aortic regurgitation fed with the same diets [aortic regurgitation on control diet (ARC), n = 16, and aortic regurgitation on fructose-rich diet (ARF), n = 13]. Fructose-rich diet was started 1 wk before surgery, and the animals were euthanized 9 wk later. SF and ARF had high circulating triglycerides. ARC and ARF developed significant LV eccentric hypertrophy after 8 wk as expected. However, ARF developed more LVH than ARC. LV ejection fraction was slightly lower in the ARF compared with ARC. The increased LVH and decreased ejection fraction could not be explained by differences in hemodynamic load. SF, ARC, and ARF had lower phosphorylation levels of the AMP kinase compared with SC. A fructose-rich diet worsened LV eccentric hypertrophy and decreased LV function in a model of chronic VO caused by AR in rats. Normal animals fed the same diet did not develop these abnormalities. Hypertriglyceridemia may play a central role in this phenomenon as well as AMP kinase activity.

Excessive cardiac insulin signaling exacerbates systolic dysfunction induced by pressure overload in rodents

Although many animal studies indicate insulin has cardioprotective effects, clinical studies suggest a link between insulin resistance (hyperinsulinemia) and heart failure (HF). Here we have demonstrated that excessive cardiac insulin signaling exacerbates systolic dysfunction induced by pressure overload in rodents. Chronic pressure overload induced hepatic insulin resistance and plasma insulin level elevation. In contrast, cardiac insulin signaling was upregulated by chronic pressure overload because of mechanical stretch-induced activation of cardiomyocyte insulin receptors and upregulation of insulin receptor and Irs1 expression. Chronic pressure overload increased the mismatch between cardiomyocyte size and vascularity, thereby inducing myocardial hypoxia and cardiomyocyte death. Inhibition of hyperinsulinemia substantially improved pressure overload-induced cardiac dysfunction, improving myocardial hypoxia and decreasing cardiomyocyte death. Likewise, the cardiomyocyte-specific reduction of insulin receptor expression prevented cardiac ischemia and hypertrophy and attenuated systolic dysfunction due to pressure overload. Conversely, treatment of type 1 diabetic mice with insulin improved hyperglycemia during pressure overload, but increased myocardial ischemia and cardiomyocyte death, thereby inducing HF. Promoting angiogenesis restored the cardiac dysfunction induced by insulin treatment. We therefore suggest that the use of insulin to control hyperglycemia could be harmful in the setting of pressure overload and that modulation of insulin signaling is crucial for the treatment of HF.

Low intrinsic aerobic exercise capacity and systemic insulin resistance are not associated with changes in myocardial substrate oxidation or insulin sensitivity

In patients, inactivity, obesity and insulin resistance are associated with increased incidence of heart failure. Rats selectively bred for low (LCR) intrinsic aerobic exercise capacity show signs of the metabolic syndrome including insulin resistance, compared to their counterparts bred for high intrinsic aerobic capacity (HCR). We reasoned that systemic insulin resistance in LCR should translate to impaired substrate oxidation and reduced insulin sensitivity in the heart. Isolated hearts were perfused in the working mode to analyze cardiac function, substrate oxidation patterns, insulin response, and oxygen consumption. After 22 generations of selective breeding, LCR displayed reduction of exercise capacity (LCR vs. HCR: distance 280 +/- 12 vs. 1,968 +/- 63 m, time 19.5 +/- 0.6 vs. 71.7 +/- 1.4 min, speed 19.2 +/- 0.3 vs. 45.3 +/- 0.7 m/min; all p < 0.05). At 21 weeks, body weight (+34%), tibia length (+6%), heart weight (+31%), and heart weight to tibia length ratio (+24%; all p < 0.05) were increased. LCR display higher random glucose, higher fasting glucose, and higher insulin levels in serum than HCR indicating the presence of insulin resistance in LCR. Here, in contrast, isolated hearts showed no differences in glucose (0.22 +/- 0.02 micromol/min/g dry) or fatty acid oxidation (0.79 +/- 0.10 micromol/min/g dry), oxygen consumption (28.3 +/- 4.1 nmol O(2)/min/g dry) or cardiac power (18.6 +/- 1.6 mW/g dry). Furthermore, sensitivity to insulin (Deltaglucose oxidation: +0.57 +/- 0.095 mumol/min/g dry) was not different between the two populations. Low intrinsic exercise capacity and systemic insulin resistance in rats are not associated with changes in cardiac substrate oxidation, insulin sensitivity, oxygen consumption, or cardiac function. The lack of cardiac insulin resistance in the face of systemic insulin resistance supports a concept of different pathomechanisms for these two conditions.

Left ventricular hypertrophy induced by overnutrition early in life

BACKGROUND AND AIMS

Human overnutrition has caused a rise in the prevalence of obesity in recent years. In addition to the deleterious effects of obesity during childhood, the long-term effects in adulthood have also been described. For instance, cardiovascular diseases, particularly left ventricular hypertrophy, and type 2 diabetes are among the diseases associated with a history of obesity. However, it remains uncertain during which period of life this association is established. Several authors have suggested that the early period of life is critical for the emergence of cardiac disorders.

METHODS AND RESULTS

In this study, we examined the impact of overnutrition on the heart morphology and stereology of obese animals using an experimental model to induce an overweight phenotype. In these animals, overfeeding during lactation was able to induce a significant increase in body weight and visceral fat starting at the 10th day of life, and this increased weight persisted until 21 days of age. Impairments in triglyceride levels and cholesterol were also observed in these animals. Moreover, an increased heart weight/tibia length ratio was observed, indicating an enlarged heart. The overfed animals also had left ventricular hypertrophy with an increased area of cardiomyocytes and a decreased vessel density.

CONCLUSIONS

Our findings showed that overnutrition during early life induced obesity and cardiac hypertrophy in the pups, perhaps due to a decrease in the intramyocardial vessel.

The emerging characterization of lysine residue deacetylation on the modulation of mitochondrial function and cardiovascular biology

There is emerging recognition of a novel fuel and redox sensing regulatory program that controls cellular adaptation via nonhistone protein lysine residue acetyl posttranslation modifications. This program functions in tissues with high energy demand and oxidative capacity and is highly enriched in the heart. Deacetylation is regulated by NAD(+)-dependent activation of the sirtuin family of proteins, whereas acetyltransferase modifications are controlled by less clearly delineated acetyltransferases. Subcellular localization specific protein targets of lysine-acetyl modification have been identified in the nucleus, cytoplasm, and mitochondria. Despite distinct subcellular localizations, these modifications appear, in large part, to modify mitochondrial properties including respiration, energy production, apoptosis, and antioxidant defenses. These mitochondrial regulatory programs are important in cardiovascular biology, although how protein acetyl modifications effects cardiovascular pathophysiology has not been extensively explored. This review will introduce the role of nonhistone protein lysine residue acetyl modifications, discuss their regulation and biochemistry and present the direct and indirect data implicating their involvement in the heart and vasculature.

omega-3 polyunsaturated fatty acid supplementation for the treatment of heart failure: mechanisms and clinical potential

Heart failure (HF) is a complex clinical syndrome with multiple aetiologies. Current treatment options can slow the progression to HF, but overall the prognosis remains poor. Clinical studies suggest that high dietary intake of the omega-3 polyunsaturated fatty acids (omega-3PUFA) found in fish oils (eicosapentaenoic and docosahexaenoic acids) may lower the incidence of HF, and that supplementation with pharmacological doses prolongs event-free survival in patients with established HF. The mechanisms for these potential benefits are complex and not well defined. It is well established that fish oil supplementation lowers plasma triglyceride levels, and more recent work demonstrates anti-inflammatory effects, including reduced circulating levels of inflammatory cytokines and arachidonic acid-derived eicosanoids, and elevated plasma adiponectin. In animal studies, fish oil favourably alters cardiac mitochondrial function. All of these effects may work to prevent the development and progression of HF. The omega-3PUFA found in plant sources, alpha-linolenic acid, may also be protective in HF; however, the evidence is not as compelling as for fish oil. This review summarizes the evidence related to use of omega-3PUFA supplementation as a potential treatment for HF and discusses possible mechanisms of action. In general, there is growing evidence that supplementation with omega-3PUFA positively impacts established pathophysiological targets in HF and has potential therapeutic utility for HF patients.

High-sugar diets increase cardiac dysfunction and mortality in hypertension compared to low-carbohydrate or high-starch diets

OBJECTIVE

Sugar consumption affects insulin release and, in hypertension, may stimulate cardiac signaling mechanisms that accelerate left ventricular hypertrophy and the development of heart failure. We investigated the effects of high-fructose or sucrose diets on ventricular function and mortality in hypertensive Dahl salt-sensitive rats.

METHODS

Rats were fed chows that were either high starch (70% starch, 10% fat by energy), high fat (20% carbohydrates, 60% fat), high fructose (61% fructose, 9% starch, 10% fat), or high sucrose (61% sucrose, 9% starch, 10% fat). Hypertension was induced by adding 6% salt to the chow (n = 8-11/group).

RESULTS

After 8 weeks of treatment, systolic blood pressure and left ventricular mass were similarly increased in all rats that were fed high-salt diets. Hypertension caused a switch in mRNA myosin heavy chain isoform from alpha to beta, and this effect was greater in the high-salt sucrose and fructose groups than in starch and fat groups. The cardiac mRNA for atrial natriuretic factor was also increased in all high-salt groups compared to respective controls, with the increase being significantly greater in the hypertensive sucrose fed group. Mortality was greater in the sucrose group (44%) compared to all the other hypertensive groups (12-18%), as was cardiomyocyte apoptosis. Left ventricular ejection fraction was lower in the high-salt sucrose group, which was due to an increase in end-systolic volume, and not increased end-diastolic volume.

CONCLUSION

Diets high in sugar accelerated cardiac systolic dysfunction and mortality in hypertension compared to either a low-carbohydrate/high-fat or high-starch diet.

Low-carbohydrate/high-fat diet attenuates pressure overload-induced ventricular remodeling and dysfunction

BACKGROUND

It is not known how carbohydrate and fat intake affect the development of left ventricular (LV) hypertrophy and contractile dysfunction in response to pressure overload. We hypothesized that a low-carbohydrate/high-fat diet prevents LV hypertrophy and dysfunction compared with high-carbohydrate diets.

METHODS AND RESULTS

Rats were fed high-carbohydrate diets composed of either starch or sucrose, or a low-carbohydrate/high-fat diet, and underwent abdominal aortic banding (AAB) for 2 months. AAB increased LV mass with all diets. LV end-diastolic and systolic volumes and the ratio of the mRNA for myosin heavy chain beta/alpha were increased with both high-carbohydrate diets but not with the low-carbohydrate/high-fat diet. Circulating levels of insulin and leptin, both stimulants for cardiac growth, were lower, and free fatty acids were higher with the low-carbohydrate/high-fat diet compared with high-carbohydrate diets. Among animals that underwent AAB, LV volumes were positively correlated with insulin and LV mass correlated with leptin.

CONCLUSION

A low-carbohydrate/high-fat diet attenuated pressure overload-induced LV remodeling compared with high-carbohydrate diets. This effect corresponded to lower insulin and leptin concentrations, suggesting they may contribute to the development of LV hypertrophy and dysfunction under conditions of pressure overload.

Long-term risk of diabetes, hypertension and left ventricular hypertrophy associated with the metabolic syndrome in a general population

OBJECTIVES

Metabolic syndrome is accompanied by an increased risk of developing diabetes mellitus. Limited or no evidence exists on whether and to what extent metabolic syndrome increases the risk of developing office hypertension, daily-life hypertension and left ventricular hypertrophy.

METHODS

In 1412 individuals representative of the population of Monza, plasma glucose, office, home and ambulatory blood pressure, and echocardiographic left ventricular mass index were measured between 1990 and 1992 and 10 years later. New onset diabetes mellitus, new onset office, home and ambulatory hypertension as well as new onset left ventricular hypertrophy were assessed in individuals with and without metabolic syndrome (Adult Treatment Panel criteria) at the first examination.

RESULTS

New onset diabetes mellitus, hypertension and left ventricular hypertrophy were all much more frequent in individuals with metabolic syndrome than in those without. In patients with metabolic syndrome, the adjusted risk of new onset diabetes mellitus was five to six times greater (P < 0.001), that of new onset office, home or ambulatory hypertension 3.5, 2.9 and 3.2 times greater (P < 0.001), respectively, and that of new onset left ventricular hypertrophy 2.6 times greater (P < 0.001). The most important predictors of new onset diabetes mellitus, hypertension and left ventricular hypertrophy were the baseline blood glucose, blood pressure and left ventricular mass index, respectively, with an independent contribution, in each condition, from other metabolic syndrome components. The metabolic syndrome as such did not have an additional predictive value.

CONCLUSION

In the general population, metabolic syndrome is associated with a marked increase in the risk not only of new onset diabetes mellitus but also of new onset office and daily-life hypertension, and left ventricular hypertrophy. This may account for the increased rate of cardiovascular morbidity and mortality exhibited with this condition in long-term studies.

Linoleate-rich high-fat diet decreases mortality in hypertensive heart failure rats compared with lard and low-fat diets

Recent studies indicate that high-fat diets may attenuate cardiac hypertrophy and contractile dysfunction in chronic hypertension. However, it is unclear whether consuming a high-fat diet improves prognosis in aged individuals with advanced hypertensive heart disease or the extent to which differences in its fatty acid composition modulate its effects in this setting. In this study, aged spontaneously hypertensive heart failure rats were administered a standard high-carbohydrate diet or high-fat diet (42% of kilocalories) supplemented with high-linoleate safflower oil or lard until death to determine their effects on disease progression and mortality. Both high-fat diets attenuated cardiac hypertrophy, left ventricular chamber dilation, and systolic dysfunction observed in rats consuming the high-carbohydrate diet. However, the lard diet significantly hastened heart failure mortality compared with the high-carbohydrate diet, whereas the linoleate diet significantly delayed mortality. Both high-fat diets elicited changes in the myocardial fatty acid profile, but neither had any effect on thromboxane excretion or blood pressure. The prosurvival effect of the linoleate diet was associated with a greater myocardial content and linoleate-enrichment of cardiolipin, an essential mitochondrial phospholipid known to be deficient in the failing heart. This study demonstrates that, despite having favorable effects on cardiac morphology and function in hypertension, a high-fat diet may accelerate or attenuate mortality in advanced hypertensive heart disease depending on its fatty acid composition. The precise mechanisms responsible for the divergent effects of the lard and linoleate-enriched diets merit further investigation but may involve diet-induced changes in the content and/or composition of cardiolipin in the heart.

Role of diet and fuel overabundance in the development and progression of heart failure

Under physiological conditions, the human heart derives energy from glucose, fatty acids, and/or lactate depending upon substrate availability, circulating hormone levels, and nutritional status. Circulating free fatty acid and glucose levels often exceed the normal range, as observed with type 2 diabetes, obesity, or physical inactivity. Chronic exposure of the heart to high plasma levels of free fatty acids may cause accumulation of toxic lipid intermediates within cardiomyocytes. Furthermore, suppression of glucose oxidation by increased fatty acid uptake shunts glucose into the oxidative pentose phosphate and hexosamine biosynthetic pathways, both of which yield potentially harmful products. Noxious derivatives of aberrant glucose and fatty acid oxidation can activate signalling cascades leading to myocyte dysfunction or death, processes termed 'glucotoxicity' and 'lipotoxicity'. This review discusses the effects of dietary extremes (e.g. high fat and high carbohydrate consumption) and substrate overabundance in the context of heart failure (HF) development and progression. Emerging data suggest that substrate excess leads to cardiac dysfunction and HF, which may be prevented or slowed by maintaining low body fat and high insulin sensitivity and consuming a diet of low glycaemic load that is high in mono- and polyunsaturated fatty acids.

Effects of a high saturated fat diet on cardiac hypertrophy and dysfunction in response to pressure overload

BACKGROUND

Dietary lipid content effects activation of peroxisome proliferator-activated receptor-alpha (PPAR-alpha) and may accelerate cardiac hypertrophy and dysfunction in response to pressure overload. This study investigated the effects of a high-fat diet on the development of cardiac hypertrophy.

METHODS AND RESULTS

C57BL/6J mice (n = 14-16/group) underwent transverse aortic constriction (TAC) or sham surgery and were fed either standard low-fat diet (STD; 10% fat) or a high-fat diet (HFD; 60% fat) for 16 weeks. Sham mice showed no differences between STD and HFD for heart mass or echocardiographic parameters despite greater plasma free fatty acid and leptin concentrations with HFD. TAC increased heart mass and decreased ejection fraction similarly in both groups. Left ventricular end systolic and diastolic diameters with TAC were increased compared with shams on the HFD (P < .05), but were not different from STD TAC mice. High-fat feeding increased expression of PPAR-alpha-regulated genes. The activity of medium chain acyl-coenzyme A dehydrogenase (MCAD), a marker of fatty acid oxidation capacity, was increased in HFD TAC mice compared with STD, consistent with PPAR-alpha activation.

CONCLUSIONS

Increased fat intake prevented the fall in MCAD activity and did not exacerbate the hypertrophic response to TAC compared with a low-fat diet.

Akt activation and augmented fibronectin production in hyperhexosemia

Dysmetabolic state in diabetes may lead to augmented synthesis of extracellular matrix (ECM) proteins. In the endothelial cells, we have previously demonstrated that glucose-induced fibronectin (FN) production and that of its splice variant, EDB(+)FN, is regulated by protein kinase B (PKB, also known as Akt). In this study, we investigated the role of Akt1 in ECM protein production in the organs affected by chronic diabetic complications. We studied Akt1/PKBalpha knockout mice and wild-type control littermates. To avoid confounding effects of systemic insulin, we used 30% galactose feeding to induce hyperhexosemia for 8 wk starting at 6 wk of age. We investigated FN mRNA, EDB(+)FN mRNA, and transforming growth factor (TGF)-beta mRNA expression, Akt phosphorylation, Akt kinase activity, and NF-kappaB and AP-1 activation in the retina, heart, and kidney. Renal and cardiac tissues were histologically examined. Galactose feeding caused significant upregulation of FN, EDB(+)FN, and TGF-beta in all tissues. FN protein levels paralleled mRNA. Such upregulation were prevented in Akt1-deficient galactose-fed mice. Galactose feeding caused ECM protein deposition in the glomeruli and in the myocardium, which was prevented in the Akt knockout mice. NF-kappaB and AP-1 activation was pronounced in galactose-fed wild-type mice and prevented in the galactose-fed Akt1/PKBalpha-deficient group. In the retina and kidney, Ser473 was the predominant site for Akt phosphorylation, whereas in the heart it was Thr308. Parallel experiment in streptozotocin-induced diabetic animals showed similar results. The data from this study indicate that hyperhexosemia-induced Akt/PKB activation may be an important mechanism leading to NF-kappaB and AP-1 activation and increased ECM protein synthesis in the organs affected by chronic diabetic complications.

Cardiac energy metabolism in obesity

Obesity results in marked alterations in cardiac energy metabolism, with a prominent effect being an increase in fatty acid uptake and oxidation by the heart. Obesity also results in dramatic changes in the release of adipokines, such as leptin and adiponectin, both of which have emerged as important regulators of cardiac energy metabolism. The link among obesity, cardiovascular disease, lipid metabolism, and adipokine signaling is complex and not well understood. However, optimizing cardiac energy metabolism in obese subjects may be one approach to preventing and treating cardiac dysfunction that can develop in this population. This review discusses what is presently known about the effects of obesity and the impact adipokines have on cardiac energy metabolism and insulin signaling. The clinical implications of obesity and energy metabolism on cardiac disease are also discussed.

Deleterious effects of sugar and protective effects of starch on cardiac remodeling, contractile dysfunction, and mortality in response to pressure overload

Little is known about the effects of the composition of dietary carbohydrate on the development of left ventricular (LV) hypertrophy (LVH) and heart failure (HF) under conditions of pressure overload. The objective of this study was to determine the effect of carbohydrate composition on LVH, LV function, and mortality in a mouse model of chronic pressure overload. Male C57BL/6J mice of 6 wk of age ( n = 14–16 mice/group) underwent transverse aortic constriction (TAC) or sham surgery and were fed either standard chow (STD; 32% corn starch, 35% sucrose, 3% maltodextrin, and 10% fat expressed as a percent of the total energy), high-starch chow (58% corn starch, 12% maltodextrin, and 10% fat), or high-fructose chow (9% corn starch, 61% fructose, and 10% fat). After 16 wk of treatment, mice with TAC fed the STD or high-fructose diets exhibited increased LV mass, larger end-diastolic and end-systolic diameters, and decreased ejection fraction compared with sham. The high-starch diet, in contrast, prevented changes in LV dimensions and contractile function. Cardiac mRNA for myosin heavy chain-β was increased dramatically in the fructose-fed banded animals, as was mortality (54% compared with 8% and 29% in the starch and STD banded groups, respectively). In conclusion, a diet high in simple sugar was deleterious, resulting in the highest mortality and expression of molecular markers of cardiac dysfunction in TAC animals compared with sham, whereas a high-starch diet blunted mortality, increases in cardiac mass, and contractile dysfunction.