3-nitrotyrosine and Cardiomyopathies

Macro- and microvascular disease are the most common causes of morbidity and mortality in patients with diabetes mellitus. Diabetic cardiovascular dysfunction represents a problem of great clinical importance underlying the development of various severe complications including retinopathy, nephropathy, neuropathy and increase the risk of stroke, hypertension and myocardial infarction. Hyperglycemic episodes, which complicate even well-controlled cases of diabetes, are closely associated with increased oxidative and nitrosative stress, which can trigger the development of diabetic complications. Hyperglycemia stimulates the production of advanced glycosylated end products, activates protein kinase C, and enhances the polyol pathway leading to increased superoxide anion formation. Superoxide anion interacts with nitric oxide, forming the potent cytotoxin peroxynitrite, which attacks various biomolecules in the vascular endothelium, vascular smooth muscle and myocardium, leading to cardiovascular dysfunction. The pathogenetic role of nitrosative stress and peroxynitrite, and downstream mechanisms including poly(ADP-ribose) polymerase (PARP) activation, is not limited to the diabetes-induced cardiovascular dysfunction, but also contributes to the development and progression of diabetic nephropathy, retinopathy and neuropathy. Accordingly, neutralization of peroxynitrite or pharmacological inhibition of PARP is a promising new approach in the therapy and prevention of diabetic complications. This review focuses on the role of nitrosative stress and downstream mechanisms including activation of PARP in diabetic complications and on novel emerging therapeutical strategies offered by neutralization of peroxynitrite and inhibition of PARP.

Topics: Animals; Cardiomyopathies; Diabetes Complications; Diabetic Angiopathies; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Endothelium, Vascular; Humans; Nitric Oxide; Oxidative Stress; Peroxynitrous Acid; Poly(ADP-ribose) Polymerases; Superoxides; Tyrosine

Sepsis aggregates undesirable immune response causing depression of ventricular myocardium and diastolic dysfunction. This present study examined the effect of a plant-derived flavone tangeretin (TG) on autophagy and reduction in myocardial dysfunction. The sepsis was induced by cecum ligation and puncture (CLP) in male Sprague-Dawley rats. Abnormal changes were seen in the heart after the sepsis induction. These abnormalities were analyzed based on the cardiac markers, namely Cardiac myosin light chain-1 (cMLC1) and Cardiac troponin I (cTnl), echocardiography, and plasma parameters, like Lactate dehydrogenase (LDH) and Creatinine kinase (CK). Microanatomy of the heart was studied using hematoxylin and eosin stained histopathological samples of cardiac tissue. Western blot technique was used to detect the nature and extent of protein with the amount of a specific RNA (gene expression) in the cardiac homogenate. Oxidative damage was analyzed using redox marker, reduced glutathione. This study successfully showed that TG attenuated sepsis-induced myocardial dysfunction by inhibiting myocardial autophagy via silencing the Phosphatase and tensin homolog (PTEN) expression and acting on the AKT/mTOR pathway. The present findings supported that TG is a novel cardioprotective therapeutic target for sepsis induced myocardial dysfunction.

Topics: Animals; Autophagy; Cardiomyopathies; Cardiotonic Agents; Cecum; Cell Death; Disease Models, Animal; Flavones; Glutathione; Heart; Ligation; Male; Myocardium; NLR Family, Pyrin Domain-Containing 3 Protein; Protein Carbonylation; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; Punctures; Rats, Sprague-Dawley; Sepsis; STAT3 Transcription Factor; TOR Serine-Threonine Kinases; Tyrosine

Sepsis is a leading cause of mortality among patients in intensive care units across the USA. Thioredoxin-1 (Trx-1) is an essential 12 kDa cytosolic protein that, apart from maintaining the cellular redox state, possesses multifunctional properties. In this study, we explored the possibility of controlling adverse myocardial depression by overexpression of Trx-1 in a mouse model of severe sepsis.. Adult C57BL/6J and Trx-1. Echocardiography analysis showed preserved cardiac function in the Trx-1. Our results indicate that overexpression of Trx-1 attenuates cardiac dysfunction during CLP. The mechanism of action may involve reduction of oxidative stress, apoptosis, and vascular permeability through activation of Trx-1/HO-1 and anti-apoptotic protein survivin.

Topics: Aldehydes; Animals; Apoptosis; Capillary Permeability; Cardiomyopathies; Carrier Proteins; Caspase 3; Disease Models, Animal; Echocardiography; Female; Heart; Heme Oxygenase-1; Immunohistochemistry; Inhibitor of Apoptosis Proteins; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myocardium; Oxidative Stress; Repressor Proteins; Sepsis; Survivin; Thioredoxins; Tyrosine

Despite increased secondary cardiovascular events in patients with ischemic cardiomyopathy (ICM), the expression of innate cardiac protective molecules in the hearts of patients with ICM is incompletely characterized. Therefore, we used a nonbiased RNAseq approach to determine whether differences in cardiac protective molecules occur with ICM.. RNAseq analysis of human control and ICM left ventricular samples demonstrated a significant decrease in

Topics: Adult; Animals; Calcium Channels, L-Type; Calcium Signaling; Calcium-Binding Proteins; Cardiomyopathies; Case-Control Studies; Disease Models, Animal; Female; Genetic Predisposition to Disease; Humans; Male; Mice, Inbred C57BL; Mice, Knockout; Middle Aged; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Oxidative Stress; Phenotype; Potassium Channels, Inwardly Rectifying; Reactive Nitrogen Species; Reactive Oxygen Species; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Tyrosine; Ventricular Dysfunction, Left; Ventricular Function, Left; Ventricular Pressure

Doxorubicin (Dox) is a highly effective antineoplastic drug. However, Dox-induced apoptosis in cardiomyocytes leads to irreversible degenerative cardiomyopathy, which limits Dox clinical application. Schisandrin B (Sch B), a dibenzocyclooctadiene derivative isolated from the fruit of Schisandra chinensis, has been shown to protect against oxidative damage in liver, heart and brain tissues in rodents. In current study, we investigated possible protective effects of Sch B against Dox-induced cardiomyopathy in mice. Mice received a single injection of Dox (20 mg/kg IP). Five days after Dox administration, left ventricular (LV) performance was significantly depressed and was improved by Sch B treatment. Sch B prevented the Dox-induced increase in lipid peroxidation, nitrotyrosine formation, and metalloproteinase activation in the heart. In addition, the increased expression of phospho-p38 MAPK and phospho-MAPK activated mitogen kinase 2 levels by Dox were significantly suppressed by Sch B treatment. Sch B also attenuated Dox-induced higher expression of LV proinflammatory cytokines, cardiomyocyte DNA damage, myocardial apoptosis, caspase-3 positive cells and phopho-p53 levels in mice. Moreover, LV expression of NADPH oxidase subunits and reactive oxygen species were significantly less in Sch B treatment mice after Dox injection. These findings suggest that Sch B attenuates Dox-induced cardiotoxicity via antioxidative and anti-inflammatory effects.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Cardiomyopathies; Cyclooctanes; Disease Models, Animal; Doxorubicin; Gene Expression Regulation; Lignans; Lipid Peroxidation; Male; Mice; Mice, Inbred C57BL; Polycyclic Compounds; Tyrosine; Ventricular Function, Left

Heart failure and related cardiac complications remains a great health challenge. We investigated the effects of upregulating heme-oxygenase (HO) on myocardial histo-pathological lesions, proinflammatory cytokines/chemokines, oxidative mediators and important markers of heart failure such as osteopontin and osteoprotergerin in N(ω)-nitro-l-arginine methyl ester (L-NAME)-induced hypertension. Treatment with the HO-inducer, heme-arginate improved myocardial morphology in L-NAME hypertensive rats by attenuating subendocardial injury, interstitial fibrosis, mononuclear-cell infiltration and cardiomyocyte hypertrophy. These were associated with the reduction of several inflammatory/oxidative mediators including chemokines/cytokines such as macrophage inflammatory protein-1 alpha (MIP-1α), macrophage chemoattractant protein-1 (MCP-1), tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, IL-1β, endothelin-1, 8-isoprostane, nitrotyrosine, and aldosterone. Similarly, heme-arginate abated the elevated levels of extracellular matrix/remodeling proteins including transforming-growth factor beta (TGF-β1) and collagen-IV in the myocardium. These were accompanied by significant reduction of proteins of heart failure such as osteopontin and osteoprotegerin. Interestingly, the cardio-protective effects of heme-arginate were associated with the potentiation of adiponectin, atrial-natriuretic peptide (ANP), HO-1, HO-activity, cyclic gnanosine monophosphate (cGMP) and the total-anti-oxidant capacity, whereas the HO-inhibitor, chromium-mesoporphyrin nullified the effects of heme-arginate, exacerbating inflammatory injury and oxidative insults. We conclude that heme-arginate therapy protects myocardial damage by potentiating the HO-adiponectin-ANP axis, which in turn suppressed the elevated levels of aldosterone, pro-inflammatory chemokines/cytokines, mononuclear-cell infiltration and oxidative stress, with concomitant reduction of extracellular matrix/remodeling proteins and heart failure proteins. These data suggest a cardio-protective role of the HO system against L-NAME-induced hypertension that could be explored in the design of novel strategies against cardiomyopathy.

Topics: Adiponectin; Aldosterone; Animals; Antioxidants; Arginine; Atrial Natriuretic Factor; Biomarkers; Blood Pressure; Cardiomyopathies; Cardiotonic Agents; Chemokine CCL2; Chemokine CCL3; Cyclic GMP; Dinoprost; Endothelin-1; Enzyme Induction; Extracellular Matrix Proteins; Heart Failure; Heme; Heme Oxygenase (Decyclizing); Hypertension; Interleukin-1beta; Interleukin-6; Male; NG-Nitroarginine Methyl Ester; Rats; Rats, Sprague-Dawley; Tumor Necrosis Factor-alpha; Tyrosine

Cardiovascular disease is one of the major causes of mortality in diabetic patients. Mounting studies have shown that garlic exhibits, possibly through its antioxidant potential, diverse biological activities. In this study, we investigated the alleviating effects of garlic oil (GO) and its two major components, diallyl disulfide (DADS) and diallyl trisulfide (DATS), on diabetic cardiomyopathy in rats. Physiological cardiac parameters were obtained using echocardiography. Apoptotic cells were evaluated using TUNEL and DAPI staining. Protein expression levels were determined using Western blotting analysis. Our findings indicated that in diabetic rat hearts significantly decreased fractional shortening percentage, increased levels of nitrotyrosine, an elevated number of TUNEL-positive cells, enhanced levels of caspase 3 expression, and decreased PI3K-Akt signaling pathway activities were observed. Furthermore, all of these alterations were reversed following both GO and DATS (or DADS) administrations through increasing PI3K-Akt signaling pathway activities and inhibiting both the death receptor-dependent and the mitochondria-dependent apoptotic pathways. In conclusion, this study shows that DATS and DADS, with the efficacy order DATS > DADS, have the therapeutic potential for ameliorating diabetic cardiomyopathy. Furthermore, the therapeutic effects of GO on diabetic cardiomyopathy should be mainly from DATS and DADS.

Topics: Allyl Compounds; Animals; Apoptosis; Cardiomyopathies; Caspase 3; Cell Survival; Diabetes Mellitus, Experimental; Disulfides; Garlic; Heart; Male; Mitochondria; Oncogene Protein v-akt; Phosphatidylinositol 3-Kinases; Rats; Rats, Wistar; Receptors, Death Domain; Signal Transduction; Sulfides; Superoxide Dismutase; Superoxide Dismutase-1; Tyrosine

Diabetic cardiomyopathy is the leading cause of heart failure among diabetic patients, and mitochondrial dysfunction has been implicated as an underlying cause in the pathogenesis. Cardiac mitochondria consist of two spatially, functionally, and morphologically distinct subpopulations, termed subsarcolemmal mitochondria (SSM) and interfibrillar mitochondria (IFM). SSM are situated beneath the plasma membrane, whereas IFM are embedded between myofibrils. The goal of this study was to determine whether spatially distinct cardiac mitochondrial subpopulations respond differently to a diabetic phenotype. Swiss-Webster mice were subjected to intraperitoneal injections of streptozotocin or citrate saline vehicle. Five weeks after injections, diabetic hearts displayed decreased rates of contraction, relaxation, and left ventricular developed pressures (P < 0.05 for all three). Both mitochondrial size (forward scatter, P < 0.01) and complexity (side scatter, P < 0.01) were decreased in diabetic IFM but not diabetic SSM. Electron transport chain complex II respiration was decreased in diabetic SSM (P < 0.05) and diabetic IFM (P < 0.01), with the decrease being greater in IFM. Furthermore, IFM complex I respiration and complex III activity were decreased with diabetes (P < 0.01) but were unchanged in SSM. Superoxide production was increased only in diabetic IFM (P < 0.01). Oxidative damage to proteins and lipids, indexed through nitrotyrosine residues and lipid peroxidation, were higher in diabetic IFM (P < 0.05 and P < 0.01, respectively). The mitochondria-specific phospholipid cardiolipin was decreased in diabetic IFM (P < 0.01) but not SSM. These results indicate that diabetes mellitus imposes a greater stress on the IFM subpopulation, which is associated, in part, with increased superoxide generation and oxidative damage, resulting in morphological and functional abnormalities that may contribute to the pathogenesis of diabetic cardiomyopathy.

Topics: Animals; Cardiolipins; Cardiomyopathies; Cell Respiration; Diabetes Mellitus, Experimental; Electron Transport Chain Complex Proteins; Female; Lipid Peroxidation; Mice; Mitochondria, Heart; Myocardial Contraction; Myocardium; Oxidative Stress; Phenotype; Superoxides; Tyrosine; Ventricular Function, Left; Ventricular Pressure

Type 1 diabetes is associated with a unique form of cardiomyopathy that is present without atherosclerosis. Redox imbalance and/or changes in vascular endothelial growth factor (VEGF) expression have been associated with diabetes-related cardiomyopathy. However, the mechanisms of these changes and their interrelationships remain unclear. Using a murine type 1 diabetes model, we tested the hypothesis that alterations in cardiac performance are associated with decreased cardiac microvascular prevalence, as well as downregulation of VEGF isoforms. We also investigated oxidative stress as a contributor to regulate individual VEGF isoforms and microvascular rarefaction. Significant and rapid hyperglycemia was observed at 1 wk post-streptozotocin (STZ) and persisted throughout the 5-wk study. Left ventricular (LV) fractional shortening was reduced at week 1 and 5 post-STZ insult relative to age-matched controls. We also observed the early reduction in E/A ratio at 1 wk. Immunostaining for CD31 and digital image analysis demonstrated a 35% reduction in microvessels/myocardial area, indicative of rarefaction, which was highly correlated with fractional shortening. Furthermore, a significant increase in the prevalence of protein 3-nitrotyrosine was observed in the diabetic cardiac tissue, which was inversely associated with microvascular rarefaction. The expressions of three VEGF isoforms were significantly reduced to different extents. The reduction of VEGF(164) was associated with GSSG accumulation. These data demonstrate that the mouse model of STZ-induced diabetes has hallmark features observed in humans with respect to nonischemic systolic and diastolic performance and microvascular rarefaction, which are associated with changes in VEGF isoform expression and redox imbalance in the myocardium.

Topics: Animals; Cardiomyopathies; Coronary Circulation; Diabetes Complications; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Disease Models, Animal; Glutathione; Glutathione Disulfide; Hyperglycemia; Male; Mice; Mice, Inbred Strains; Microcirculation; Myocardium; Oxidants; Oxidation-Reduction; Specific Pathogen-Free Organisms; Stroke Volume; Tyrosine; Vascular Endothelial Growth Factor A; Ventricular Function, Left

We aimed to test whether attenuation of early-phase cardiac cell death can prevent diabetic cardiomyopathy.. Our previous study showed that cardiac apoptosis as a major early cellular response to diabetes is induced by hyperglycemia-derived oxidative stress that activates a mitochondrial cytochrome c-mediated caspase-3 activation pathway. Metallothionein (MT) as a potent antioxidant prevents the development of diabetic cardiomyopathy.. Diabetes was induced by a single dose of streptozotocin (STZ) (150 mg/kg) in cardiac-specific, metallothionein-overexpressing transgenic (MT-TG) mice and wild-type (WT) controls. On days 7, 14, and 21 after STZ treatment, cardiac apoptosis was examined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and caspase-3 activation. Cardiomyopathy was evaluated by cardiac ultrastructure and fibrosis in the diabetic mice 6 months after STZ treatment.. A significant reduction in diabetes-induced increases in TUNEL-positive cells, caspase-3 activation, and cytochrome c release from mitochondria was observed in the MT-TG mice as compared to WT mice. Cardiac protein nitration (3-nitrotyrosine [3-NT]) and lipid peroxidation were significantly increased, and there was an increase in mitochondrial oxidized glutathione and a decrease in mitochondrial reduced glutathione in the WT, but not in the MT-TG, diabetic mice. Double staining for cardiomyocytes with alpha sarcomeric actin and caspase-3 or 3-NT confirmed the cardiomyocyte-specific effects. A significant prevention of diabetic cardiomyopathy and enhanced animal survival were observed in the MT-TG diabetic mice as compared to WT diabetic mice.. These results suggest that attenuation of early-phase cardiac cell death by MT results in a significant prevention of the development of diabetic cardiomyopathy. This process is mediated by MT suppression of mitochondrial oxidative stress.

Topics: Actins; Animals; Antioxidants; Apoptosis; Cardiomyopathies; Caspase 3; Cell Death; Cytochromes c; Diabetes Mellitus, Experimental; Enzyme Activation; Glutathione; Glutathione Disulfide; Lipid Peroxidation; Metallothionein; Mice; Mice, Transgenic; Mitochondria, Heart; Myocardium; Myocytes, Cardiac; Oxidative Stress; Sarcomeres; Survival Analysis; Tyrosine

The mechanisms of metallothionein prevention of diabetic cardiomyopathy are largely unknown. The present study was performed to test whether inhibition of nitrosative damage is involved in metallothionein prevention of diabetic cardiomyopathy. Cardiac-specific metallothionein-overexpressing transgenic (MT-TG) mice and wild-type littermate controls were treated with streptozotocin (STZ) by a single intraperitoneal injection, and both developed diabetes. However, the development of diabetic cardiomyopathy, revealed by histopathological and ultrastructural examination, serum creatine phosphokinase, and cardiac hemodynamic analysis, was significantly observed only in the wild-type, but not in MT-TG, diabetic mice 2 weeks and 6 months after STZ treatment. Formations of superoxide and 3-nitrotyrosine (3-NT), a marker for peroxynitrite-induced protein damage, were detected only in the heart of wild-type diabetic mice. Furthermore, primary cultures of cardiomyocytes from wild-type and MT-TG mice were exposed to lipopolysaccharide/tumor necrosis factor-alpha for generating intracellular peroxynitrite. Increases in 3-NT formation and cytotoxicity were observed in wild-type, but not in MT-TG, cardiomyocytes. Either urate, a peroxynitrite-specific scavenger, or Mn(111) tetrakis 1-methyl 4-pyridyl porphyrin pentachloride (MnTMPyP), a superoxide dismutase mimic, significantly inhibited the formation of 3-NT along with a significant prevention of cytotoxicity. These results thus suggest that metallothionein prevention of diabetic cardiomyopathy is mediated, at least in part, by suppression of superoxide generation and associated nitrosative damage.

Topics: Animals; Cardiomyopathies; Diabetes Complications; Gene Expression; Heart Diseases; Male; Metallothionein; Mice; Mice, Transgenic; Nitrosation; Superoxides; Tyrosine

Heart failure and hypertension have each been linked to an induction of oxidative stress transduced by neurohormones, such as angiotensin II and catecholamines. Herein, we hypothesized that aldosterone (ALDO) likewise induces oxidative stress and accounts for a proinflammatory/fibrogenic phenotype that appears at vascular and nonvascular sites of injury found in both right and left ventricles in response to ALDO/salt treatment and that would be sustained with chronic treatment. Uninephrectomized rats received ALDO (0.75 micro g/hour) together with 1% dietary NaCl, for 3, 4, or 5 weeks. Other groups received this regimen in combination with an ALDO receptor antagonist, spironolactone (200 mg/kg p.o. daily), or an antioxidant, either pyrrolidine dithiocarbamate (PDTC) (200 mg/kg s.c. daily) or N-acetylcysteine (NAC) (200 mg/kg i.p. daily). Unoperated and untreated age- and gender-matched rats served as controls. We monitored spatial and temporal responses in molecular and cellular events using serial, coronal sections of right and left ventricles. Our studies included: assessment of systolic blood pressure; immunohistochemical detection of NADPH oxidase expression and activity; analysis of redox-sensitive nuclear factor-kappaB activation; in situ localization of intercellular adhesion molecule-1, monocyte chemoattractant protein-1, and tumor necrosis factor-alpha mRNA expression; monitoring cell growth and infiltration of macrophages and T cells; and analysis of the appearance and quantity of fibrous tissue accumulation. At week 3 of ALDO/salt treatment and comparable to controls, there was no evidence of oxidative stress or pathological findings in the heart. However, at weeks 4 and 5 of treatment, increased gp91(phox) and 3-nitrotyrosine expression and persistent activation of RelA were found in endothelial cells and inflammatory cells that appeared in the perivascular space of intramural coronary arteries and at sites of lost cardiomyocytes in both ventricles. Coincident in time and space with these events was increased mRNA expression of intercellular adhesion molecule-1, monocyte chemoattractant protein-1, and tumor necrosis factor-alpha. Macrophages, lymphocytes, and proliferating endothelial and vascular smooth muscle cells and fibroblast-like cells were seen at each of these sites, together with an accumulation of fibrillar collagen, or fibrosis, as evidenced by a significant increase in ventricular collagen volume fraction. Co-treatment with spiron

Topics: Aldosterone; Animals; Antioxidants; Cardiomyopathies; Cell Division; Cell Movement; Fibrosis; Heart; Immunologic Factors; Inflammation; Lymphocytes; Macrophages; Male; Mineralocorticoid Receptor Antagonists; Monocytes; Myocardium; NADPH Oxidases; NF-kappa B; Oxidative Stress; Rats; Rats, Sprague-Dawley; RNA, Messenger; Spironolactone; Tyrosine

Stimulation of the local renin-angiotensin system and apoptosis characterize the diabetic heart. Because IGF-1 reduces angiotensin (Ang) II and apoptosis, we tested whether streptozotocin-induced diabetic cardiomyopathy was attenuated in IGF-1 transgenic mice (TGM). Diabetes progressively depressed ventricular performance in wild-type mice (WTM) but had no hemodynamic effect on TGM. Myocyte apoptosis measured at 7 and 30 days after the onset of diabetes was twofold higher in WTM than in TGM. Myocyte necrosis was apparent only at 30 days and was more severe in WTM. Diabetic nontransgenic mice lost 24% of their ventricular myocytes and showed a 28% myocyte hypertrophy; both phenomena were prevented by IGF-1. In diabetic WTM, p53 was increased in myocytes, and this activation of p53 was characterized by upregulation of Bax, angiotensinogen, Ang type 1 (AT(1)) receptors, and Ang II. IGF-1 overexpression decreased these biochemical responses. In vivo accumulation of the reactive O(2) product nitrotyrosine and the in vitro formation of H(2)O(2)-(.)OH in myocytes were higher in diabetic WTM than TGM. Apoptosis in vitro was detected in myocytes exhibiting high H(2)O(2)-(.)OH fluorescence, and apoptosis in vivo was linked to the presence of nitrotyrosine. H(2)O(2)-(.)OH generation and myocyte apoptosis in vitro were inhibited by the AT(1) blocker losartan and the O(2) scavenger TIRON: In conclusion, IGF-1 interferes with the development of diabetic myopathy by attenuating p53 function and Ang II production and thus AT(1) activation. This latter event might be responsible for the decrease in oxidative stress and myocyte death by IGF-1.

Topics: Angiotensin II; Animals; Apoptosis; Cardiomyopathies; Diabetic Angiopathies; DNA; Insulin-Like Growth Factor I; Mice; Mice, Transgenic; Myocardium; Oxidative Stress; Reactive Oxygen Species; Renin-Angiotensin System; Tissue Distribution; Tumor Suppressor Protein p53; Tyrosine; Ventricular Function