scholarly journals Sirtuin 1 ablation in endothelial cells is associated with impaired angiogenesis and diastolic dysfunction

2014 ◽  
Vol 307 (12) ◽  
pp. H1691-H1704 ◽  
Author(s):  
Julien Maizel ◽  
Sandhya Xavier ◽  
Jun Chen ◽  
Chi Hua Sarah Lin ◽  
Radovan Vasko ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Diastolic Dysfunction ◽  
Mrna Expression ◽  
Ex Vivo ◽  
Hypoxia Inducible Factor ◽  
Capillary Density ◽  
Left Ventricular ◽  
Sirtuin 1 ◽  
Aortic Constriction ◽  
Aortic Explants

Discordant myocardial growth and angiogenesis can explain left ventricular (LV) hypertrophy progressing toward heart failure with aging. Sirtuin 1 expression declines with age; therefore we explored the role played by angiogenesis and Sirtuin 1 in the development of cardiomyopathy. We compared the cardiac function of 10- to 15-wk-old (wo), 30–40 wo, and 61–70 wo endothelial Sirtuin 1-deleted (Sirt1endo−/−) mice and their corresponding knockout controls (Sirt1Flox/Flox). After 30–40 wk, Sirt1endo−/− animals exhibited diastolic dysfunction (DD), decreased mRNA expression of Serca2a in the LV, and decreased capillary density compared with control animals despite a similar VEGFa mRNA expression. However, LV fibrosis and hypoxia-inducible factor (HIF)1α expression were not different. The creation of a transverse aortic constriction (TAC) provoked more severe DD and LV fibrosis in Sirt1endo−/− compared with control TAC animals. Although the VEGFa mRNA expression was not different and the protein expression of HIF1α was higher in the Sirt1endo−/− TAC animals, capillary density remained reduced. In cultured endothelial cells administration of Sirtuin 1 inhibitor decreased mRNA expression of VEGF receptors FLT 1 and FLK 1. Ex vivo capillary sprouting from aortic explants showed impaired angiogenic response to VEGF in the Sirt1endo−/− mice. In conclusion, the data demonstrate 1) a defect in angiogenesis preceding development of DD; 2) dispensability of endothelial Sirtuin 1 under unstressed conditions and during normal aging; and 3) impaired angiogenic adaptation and aggravated DD in Sirt1endo−/− mice challenged with LV overload.

scholarly journals Cardioprotective Effects of PPARβ/δ Activation against Ischemia/Reperfusion Injury in Rat Heart Are Associated with ALDH2 Upregulation, Amelioration of Oxidative Stress and Preservation of Mitochondrial Energy Production

2021 ◽  
Vol 22 (12) ◽  
pp. 6399
Author(s):  
Ioanna Papatheodorou ◽  
Eleftheria Galatou ◽  
Georgios-Dimitrios Panagiotidis ◽  
Táňa Ravingerová ◽  
Antigone Lazou
Keyword(s):  
Oxidative Stress ◽  
Mrna Expression ◽  
Energy Production ◽  
Citrate Synthase ◽  
Ischemia Reperfusion Injury ◽  
Ex Vivo ◽  
Uncoupling Protein ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Isocitrate Dehydrogenase 2

Accumulating evidence support the cardioprotective properties of the nuclear receptor peroxisome proliferator activated receptor β/δ (PPARβ/δ); however, the underlying mechanisms are not yet fully elucidated. The aim of the study was to further investigate the mechanisms underlying PPARβ/δ-mediated cardioprotection in the setting of myocardial ischemia/reperfusion (I/R). For this purpose, rats were treated with PPARβ/δ agonist GW0742 and/or antagonist GSK0660 in vivo and hearts were subjected to ex vivo global ischemia followed by reperfusion. PPARβ/δ activation improved left ventricular developed pressure recovery, reduced infarct size (IS) and incidence of reperfusion-induced ventricular arrhythmias while it also up-regulated superoxide dismutase 2, catalase and uncoupling protein 3 resulting in attenuation of oxidative stress as evidenced by the reduction in 4-hydroxy-2-nonenal protein adducts and protein carbonyl formation. PPARβ/δ activation also increased both mRNA expression and enzymatic activity of aldehyde dehydrogenase 2 (ALDH2); inhibition of ALDH2 abrogated the IS limiting effect of PPARβ/δ activation. Furthermore, upregulation of PGC-1α and isocitrate dehydrogenase 2 mRNA expression, increased citrate synthase activity as well as mitochondrial ATP content indicated improvement in mitochondrial content and energy production. These data provide new mechanistic insight into the cardioprotective properties of PPARβ/δ in I/R pointing to ALDH2 as a direct downstream target and suggesting that PPARβ/δ activation alleviates myocardial I/R injury through coordinated stimulation of the antioxidant defense of the heart and preservation of mitochondrial function.

Abstract 16485: The Nitroxyl Donor 1-Nitrosocyclohexyl Acetate Limits Cardiac Superoxide Upregulation and Diastolic Dysfunction in a Mouse Model of Diabetic Cardiomyopathy

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Rebecca H Ritchie ◽  
Nga Cao ◽  
Yung George Wong ◽  
Sarah Rosli ◽  
Helen Kiriazis ◽  
...  
Keyword(s):  
Heart Failure ◽  
Mouse Model ◽  
Diastolic Dysfunction ◽  
Diabetic Cardiomyopathy ◽  
Ex Vivo ◽  
Systolic Function ◽  
Left Ventricular ◽  
Cardiomyocyte Hypertrophy ◽  
Lv Diastolic Dysfunction ◽  
The Impact

Nitroxyl (HNO), a redox congener of NO•, is a novel regulator of cardiovascular function combining vasodilator and positive inotropic properties. Our previous studies have demonstrated these properties occur concomitantly in the intact heart; HNO moreover also exhibits antihypertrophic and superoxide-suppressing actions. HNO donors may thus offer favorable actions in heart failure. The impact of chronic HNO donor administration has however yet to be reported in this context. We tested the hypothesis that the HNO donor 1-nitrosocyclohexyl acetate (1-NCA) limits cardiomyocyte hypertrophy and left ventricular (LV) diastolic dysfunction in a mouse model of diabetic cardiomyopathy in vivo. Male 6 week-old FVB/N mice received either streptozotocin (55 mg/kg/day i.p. for 5 days, n=17), to induce type 1 diabetes, or citrate vehicle (n=16). After 4 weeks of hyperglycemia, mice were allocated to 1-NCA therapy (83mg/kg/day i.p.) or vehicle, and followed for a further 4 weeks. As shown in the table, blood glucose was unaffected by 1-NCA. LV diastolic dysfunction was evident in diabetic mice, measured as echocardiography-derived A wave velocity, deceleration time and E:A ratio; LV systolic function was preserved. Diabetes-induced diastolic dysfunction was accompanied by increased LV cardiomyocyte size, hypertrophic and pro-fibrotic gene expression, and upregulation of LV superoxide. These characteristics of diabetic cardiomyopathy were largely prevented by 1-NCA treatment. Selectivity of 1-NCA as a donor of HNO versus NO• was demonstrated by the sensitivity of the coronary vasodilation response of 1-NCA to the HNO scavenger L-cysteine (4mM), but not to the NO• scavenger hydroxocobalamin (50μM), in the normal rat heart ex vivo (n=3-7). Collectively, our studies provide the first evidence that HNO donors may represent a promising new strategy for the treatment of diabetic cardiomyopathy, and implies their therapeutic efficacy in settings of chronic heart failure.

Abstract P490: Vascular Rarefaction And Decreased Angiogenic Potential In The Development Of Left Ventricular Diastolic Dysfunction In Heart Failure With Preserved Ejection Fraction

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Katie Anne Fopiano ◽  
Yanna Tian ◽  
Vadym Buncha ◽  
Liwei Lang ◽  
Zsolt Bagi
Keyword(s):  
Heart Failure ◽  
Ejection Fraction ◽  
Diastolic Dysfunction ◽  
Rat Model ◽  
Ex Vivo ◽  
Diastolic Heart Failure ◽  
Left Ventricular ◽  
Coronary Microvascular Dysfunction ◽  
Preserved Ejection Fraction ◽  
Angiogenic Potential

Coronary microvascular dysfunction (CMD) develops in patients with heart failure with preserved ejection fraction (HFpEF, also known as diastolic heart failure), but the nature of the underlying pathomechanisms behind this prevalent disease remain poorly understood. The hypothesis tested was that coronary microvascular rarefaction contributes to left ventricle (LV) diastolic function in HFpEF. The obese ZSF1 rat model of human HFpEF was employed and using transthoracic echocardiography it was found that 18-week-old male obese ZSF1 rats exhibited a significantly reduced E/A ratio (E=early, A=late mitral inflow peak velocities) and increased DT (E wave deceleration time) with no change in ejection fraction, indicating diastolic dysfunction. Coronary arteriolar and capillary trees were labeled using Tomato Lectin (Lycopersicon esculentum) DyLight®594 and were imaged by fluorescent confocal microscopy to generate image stacks for 3D reconstruction. Unbiased automated tracing of the microvasculature was done using VesselLucida360 software (MBF) followed by a morphometric analysis (VesselLucida Explorer). It was found that total vessel length and the number of vessel’s branching nodes were reduced in the obese ZSF1 rats, whereas the total vessel’s volumes remained consistent, when compared to the lean ZSF1 controls. These changes in the microvasculature were accompanied by decreased angiogenesis in the coronary arteries in the obese ZSF1 rats when compared to the lean ZSF1 rats using an ex vivo endothelial sprouting assay. From these results, it was concluded that vascular rarefaction and decreased angiogenesis both play a role in the development of LV diastolic dysfunction in the obese ZSF1 rat model of human HFpEF.

Abstract P300: Cardiac Ly6C high Monocyte Accumulation and Remodeling Depend on the Mineralocorticoid Receptor in Endothelial Cells

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Achim Lother ◽  
Aurelia Hübner ◽  
Ingo Hilgendorf ◽  
Tilman Schnick ◽  
Martin Moser ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Diastolic Dysfunction ◽  
Mineralocorticoid Receptor ◽  
Cardiac Fibrosis ◽  
Ventricular Remodeling ◽  
Interstitial Fibrosis ◽  
Left Ventricular Remodeling ◽  
Marker Gene ◽  
Pressure Overload ◽  
Left Ventricular

Introduction: Inflammation is a key driver for the development of cardiac fibrosis and diastolic dysfunction. Aldosterone promotes the expression of adhesion molecules and vascular inflammation. Thus, the goal of the present study was to examine the significance of endothelial MR for pressure overload induced cardiac inflammation and remodeling. Methods and results: Mice with endothelial cell-specific deletion of the mineralocorticoid receptor (MR Cdh5Cre ) were generated using the Cre/loxP system. MR Cdh5Cre and Cre-negative littermates (MR wildtype ) underwent transverse aortic constriction (TAC, n=5-7 per group). After two weeks of pressure overload echocardiography revealed diastolic dysfunction in MR wildtype (mitral valve E acceleration time TAC 15.7 ± 0.5 vs. sham 12.8 ± 0.4 ms, P<0.05) but not in MR Cdh5Cre mice (TAC 11.2 ± 0.6 vs. sham 12.2 ± 0.9 ms, n.s.). Cardiac hypertrophy (ventricle weight 143.2 ± 5.2 vs. MR wildtype 167.3 ± 6.7 mg, P<0.001) and interstitial fibrosis (sirius red stained area 8.2 ± 4.7 vs. MR wildtype 13.5 ± 4.5 %, P<0.05) following TAC were attenuated in MR Cdh5Cre mice. mRNA expression of atrial natriuretic peptide ( Nppa , 2429 ± 1230 vs. MR wildtype 7051 ± 3182 copies/10 4 copies Rps29 , P<0.01) or the fibrosis marker gene collagen 1a1 ( Col1a1 , 256 ± 89 vs. MR wildtype 432 ± 165 copies/10 4 copies Rps29 , P<0.05) as determined by qRT-PCR confirmed these findings. Cardiac leukocytes were quantitatively analyzed by fluorescence assisted cell sorting using specific antibodies. Numbers of CD45 + leukocytes were similarly increased after TAC in the hearts of both genotypes (MR Cdh5Cre 3840 ± 443 vs. MR wildtype 4051 ± 385 /mg tissue, n.s.). Subtype analysis revealed a shift towards CD45 + CD11b + F4/80 low Ly6C high monocytes vs. CD45 + CD11b + F4/80 high Ly6C low macrophages in the heart of MR wildtype (TAC 20 ± 6 vs. sham 4 ± 1 % of CD45 + CD11b + , P<0.05) but not of MR Cdh5Cre mice (TAC 6 ± 2 vs. sham 3 ± 1 % of CD45 + CD11b + , n.s.). Conclusion: MR deletion from endothelial cells ameliorates left ventricular remodeling and diastolic dysfunction after pressure overload. The protective effect of endothelial MR deletion is associated with a shift towards less pro-inflammatory Ly6C high monocytes and more reparative Ly6C low macrophages.

scholarly journals Resveratrol Ameliorates Cardiac Remodeling in a Murine Model of Heart Failure With Preserved Ejection Fraction

2021 ◽  
Vol 12 ◽  
Author(s):  
Liyun Zhang ◽  
Juan Chen ◽  
Lianhua Yan ◽  
Qin He ◽  
Han Xie ◽  
...  
Keyword(s):  
Heart Failure ◽  
Ejection Fraction ◽  
Mrna Expression ◽  
Cardiac Remodeling ◽  
Transcriptional Activity ◽  
Left Ventricular ◽  
Sirtuin 1 ◽  
Neonatal Rat ◽  
Preserved Ejection Fraction ◽  
Underlying Mechanisms

Objective: Accumulating evidence suggested that resveratrol (RES) could protect against adverse cardiac remodeling induced by several cardiovascular diseases. However, the role of RES in the setting of heart failure with preserved ejection fraction (HFpEF) and the underlying mechanisms of its action remain understood. This study was to determine whether RES could ameliorate HFpEF-induced cardiac remodeling and its mechanisms.Methods:In vivo, C57BL/6 mice served as either the sham or the HFpEF model. The HFpEF mice model was induced by uninephrectomy surgery and d-aldosterone infusion. RES (10 mg/kg/day, ig) or saline was administered to the mice for four weeks. In vitro, transforming growth factor β1 (TGF-β1) was used to stimulate neonatal rat cardiac fibroblasts (CFs) and Ex-527 was used to inhibit sirtuin 1 (Sirt1) in CFs. Echocardiography, hemodynamics, western blotting, quantitative real-time PCR, histological analysis, immunofluorescence, and ELISA kits were used to evaluate cardiac remodeling induced by HFpEF. Sirt1 and Smad3 expressions were measured to explore the underlying mechanisms of RES.Results: HFpEF mice developed left ventricular hypertrophy, preserved ejection fraction, diastolic dysfunction, and pulmonary congestion. Moreover, HFpEF mice showed increased infiltration of neutrophils and macrophages into the heart, including increased interleukin (IL)-1β, IL-6, and TNF-α. We also observed elevated M1 macrophages and decreased M2 macrophages, which were exhibited by increased mRNA expression of M1 markers (iNOS, CD86, and CD80) and decreased mRNA expression of M2 markers (Arg1, CD163, and CD206) in HFpEF hearts. Moreover, HFpEF hearts showed increased levels of intracellular reactive oxygen species (ROS). Importantly, HFpEF mice depicted increased collagen-I and -III and TGF-β mRNA expressions and decreased protein expression of phosphorylated endothelial nitric-oxide synthase (p-eNOS). Results of western blot revealed that the activated TGF-β/Smad3 signaling pathway mediated HFpEF-induced cardiac remodeling. As expected, this HFpEF-induced cardiac remodeling was reversed when treated with RES. RES significantly decreased Smad3 acetylation and inhibited Smad3 transcriptional activity induced by HFpEF via activating Sirt1. Inhibited Sirt1 with Ex-527 increased Smad3 acetylation, enhanced Smad3 transcriptional activity, and offset the protective effect of RES on TGF-β–induced cardiac fibroblast–myofibroblast transformation in CFs.Conclusion: Our results suggested that RES exerts a protective action against HFpEF-induced adverse cardiac remodeling by decreasing Smad3 acetylation and transcriptional activity via activating Sirt1. RES is expected to be a novel therapy option for HFpEF patients.

scholarly journals Loss of Endothelial Hypoxia Inducible Factor‐Prolyl Hydroxylase 2 Induces Cardiac Hypertrophy and Fibrosis

2021 ◽  
Author(s):  
Zhiyu Dai ◽  
Jianding Cheng ◽  
Bin Liu ◽  
Dan Yi ◽  
Anlin Feng ◽  
...  
Keyword(s):  
Heart Failure ◽  
Endothelial Cells ◽  
Left Ventricular Hypertrophy ◽  
Cardiac Hypertrophy ◽  
Ventricular Hypertrophy ◽  
Hypoxia Inducible Factor ◽  
Left Ventricular ◽  
Sequencing Analysis ◽  
Dependent Manner

Background Cardiac hypertrophy and fibrosis are common adaptive responses to injury and stress, eventually leading to heart failure. Hypoxia signaling is important to the (patho)physiological process of cardiac remodeling. However, the role of endothelial PHD2 (prolyl‐4 hydroxylase 2)/hypoxia inducible factor (HIF) signaling in the pathogenesis of cardiac hypertrophy and heart failure remains elusive. Methods and Results Mice with Egln1 Tie2Cre ( Tie2 ‐Cre‐mediated deletion of Egln1 [encoding PHD2]) exhibited left ventricular hypertrophy evident by increased thickness of anterior and posterior wall and left ventricular mass, as well as cardiac fibrosis. Tamoxifen‐induced endothelial Egln1 deletion in adult mice also induced left ventricular hypertrophy and fibrosis. Additionally, we observed a marked decrease of PHD2 expression in heart tissues and cardiovascular endothelial cells from patients with cardiomyopathy. Moreover, genetic ablation of Hif2a but not Hif1a in Egln1 Tie2Cre mice normalized cardiac size and function. RNA sequencing analysis also demonstrated HIF‐2α as a critical mediator of signaling related to cardiac hypertrophy and fibrosis. Pharmacological inhibition of HIF‐2α attenuated cardiac hypertrophy and fibrosis in Egln1 Tie2Cre mice. Conclusions The present study defines for the first time an unexpected role of endothelial PHD2 deficiency in inducing cardiac hypertrophy and fibrosis in an HIF‐2α–dependent manner. PHD2 was markedly decreased in cardiovascular endothelial cells in patients with cardiomyopathy. Thus, targeting PHD2/HIF‐2α signaling may represent a novel therapeutic approach for the treatment of pathological cardiac hypertrophy and failure.

Sepiapterin prevents left ventricular hypertrophy and dilatory remodeling induced by pressure overload in rats

2015 ◽  
Vol 309 (10) ◽  
pp. H1782-H1791 ◽  
Author(s):  
Kei Yoshioka ◽  
Hajime Otani ◽  
Takayuki Shimazu ◽  
Masanori Fujita ◽  
Toshiji Iwasaka ◽  
...  
Keyword(s):  
Ventricular Hypertrophy ◽  
Interstitial Fibrosis ◽  
Pressure Overload ◽  
Capillary Density ◽  
Left Ventricular ◽  
Cardiomyocyte Hypertrophy ◽  
Salvage Pathway ◽  
Aortic Constriction ◽  
Beneficial Effects ◽  
Lv Remodeling

Uncoupling of nitric oxide (NO) synthase (NOS) has been implicated in left ventricular (LV) hypertrophy (LVH) and dilatory remodeling induced by pressure overload. We investigated whether administration of sepiapterin, a substrate of the salvage pathway of tetrahydrobiopterin synthesis, prevents LVH and dilatory LV remodeling by inhibiting NOS uncoupling and increasing bioavailable NO. Pressure overload was induced in rats by transverse aortic constriction (TAC). Concentric LVH developed during 8 wk after TAC, and dilatory LV remodeling and dysfunction developed between 8 and 16 wk after TAC associated with a decrease in capillary density. Oral administration of sepiapterin or the superoxide/peroxynitrite scavenger N-(2-mercaptopropionyl)-glycine for 8 wk after TAC inhibited oxidative stress, but only sepiapterin increased bioavailable NO and inhibited cardiomyocyte hypertrophy associated with a further increase in capillary density. When sepiapterin was administered between 8 and 16 wk after TAC, cardiomyocyte hypertrophy was regressed and capillary density was restored. This was associated with the inhibition of interstitial fibrosis and dilatory LV remodeling. N-nitro-l-arginine methyl ester abrogated all the beneficial effects of sepiapterin in rats with TAC. These results suggest that sepiapterin prevents concentric LVH and dilatory remodeling after TAC primarily by increasing the bioavailability of NO.

scholarly journals HDAC inhibition improves cardiopulmonary function in a feline model of diastolic dysfunction

2020 ◽  
Vol 12 (525) ◽  
pp. eaay7205 ◽  
Author(s):  
Markus Wallner ◽  
Deborah M. Eaton ◽  
Remus M. Berretta ◽  
Laura Liesinger ◽  
Matthias Schittmayer ◽  
...  
Keyword(s):  
Diastolic Dysfunction ◽  
Diastolic Pressure ◽  
Ex Vivo ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Blood Oxygenation ◽  
Hdac Inhibition ◽  
Major Health Problem ◽  
Feline Model

Heart failure with preserved ejection fraction (HFpEF) is a major health problem without effective therapies. This study assessed the effects of histone deacetylase (HDAC) inhibition on cardiopulmonary structure, function, and metabolism in a large mammalian model of pressure overload recapitulating features of diastolic dysfunction common to human HFpEF. Male domestic short-hair felines (n = 31, aged 2 months) underwent a sham procedure (n = 10) or loose aortic banding (n = 21), resulting in slow-progressive pressure overload. Two months after banding, animals were treated daily with suberoylanilide hydroxamic acid (b + SAHA, 10 mg/kg, n = 8), a Food and Drug Administration–approved pan-HDAC inhibitor, or vehicle (b + veh, n = 8) for 2 months. Echocardiography at 4 months after banding revealed that b + SAHA animals had significantly reduced left ventricular hypertrophy (LVH) (P < 0.0001) and left atrium size (P < 0.0001) versus b + veh animals. Left ventricular (LV) end-diastolic pressure and mean pulmonary arterial pressure were significantly reduced in b + SAHA (P < 0.01) versus b + veh. SAHA increased myofibril relaxation ex vivo, which correlated with in vivo improvements of LV relaxation. Furthermore, SAHA treatment preserved lung structure, compliance, blood oxygenation, and reduced perivascular fluid cuffs around extra-alveolar vessels, suggesting attenuated alveolar capillary stress failure. Acetylation proteomics revealed that SAHA altered lysine acetylation of mitochondrial metabolic enzymes. These results suggest that acetylation defects in hypertrophic stress can be reversed by HDAC inhibitors, with implications for improving cardiac structure and function in patients.

Abstract 13311: Cardiac SIRT1 Deficiency Sensitizes Myocardium to Ischemia and Reperfusion Injury

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Jinli Wang ◽  
Yina Ma ◽  
Wanqing Sun ◽  
George Techiryan ◽  
Yanqing Wang ◽  
...  
Keyword(s):  
Infarct Size ◽  
Therapeutic Potential ◽  
Ex Vivo ◽  
Heart Function ◽  
Interleukin 1 ◽  
Left Ventricular ◽  
Sirtuin 1 ◽  
Ischemia And Reperfusion ◽  
Ischemia And Reperfusion Injury ◽  
Physiological Conditions

Introduction: A “longevity” gene, sirtuin 1 (SIRT1) is a conserved NAD + -dependent protein deacetylase that regulates life span extension. We have reported that SIRT1 is down-regulated in the aged heart which shows larger infarct size and deteriorative heart function during ischemia and reperfusion (I/R) compared with that of young heart. Hypothesis: Cardiac specific SIRT1 deficiency could increase the sensitivity of heart to ischemic insults caused by ischemia and reperfusion. Methods: Male SIRT1 flox/flox mice and tamoxifen-inducible, cardiac-specific SIRT1 KO mice were subjected to I/R, which were induced by occluding the left anterior descending coronary (LAD) and subsequent releasing it. Langendorff-perfused heart model was used to monitor the heart function during I/R. Results: Adult cardiac-specific SIRT1 KO demonstrated significant cardiac hypertrophy, fibrosis and macrophage infiltration under normal physiological conditions versus the SIRT1 flox/flox hearts by immunohistochemical staining (all p<0.05). The cardiac functions measured by the pressure-volume loop remained normal in SIRT1 KO mice as compared with SIRT1 flox/flox mice under physiological conditions. The ex vivo heart perfusion results showed that the heart rate-left ventricular developed pressure product in SIRT1 KO hearts was decreased by 30% versus the SIRT1 flox/flox hearts (p<0.05), and the infarct size of SIRT1 KO hearts was 1.7-fold larger than that of SIRT1 flox/flox hearts (p<0.05). The immunoblotting data demonstrated that SIRT1 KO hearts had impaired responsive activation of AMP-activated protein kinase (AMPK) signaling during I/R versus the SIRT1 flox/flox hearts. Furthermore, real-time qRT-PCR showed that cardiac SIRT1 KO resulted in up-regulation of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin-1 β and growth differentiation factor15 (GDF15), as well as a heart failure marker ANP (atrial natriuretic peptide) versus SIRT1 flox/flox hearts during I/R. Conclusions: SIRT1 plays a vital role in regulation of myocardial infarction, heart function and inflammation induced by I/R in the heart. SIRT1 specific agonists may have therapeutic potential for treatment of ischemic heart disease.

Response of the hypertrophied left ventricle to tachycardia: importance of maturation

1993 ◽  
Vol 264 (3) ◽  
pp. H983-H993 ◽  
Author(s):  
A. M. Fujii ◽  
T. Aoyagi ◽  
M. F. Flanagan ◽  
T. Takahashi ◽  
E. Bennett-Guerrero ◽  
...  
Keyword(s):  
Diastolic Dysfunction ◽  
Pressure Overload ◽  
Capillary Density ◽  
Left Ventricular ◽  
Mrna Levels ◽  
Adult Sheep ◽  
Flow Reserve ◽  
Abnormal Response ◽  
Rapid Pacing ◽  
Isovolumic Relaxation

Pressure overload left ventricular (LV) hypertrophy (LVH) induces ventricular dysfunction during stress, which is commonly attributed to diminished myocardial capillary density and ischemia. Immature hearts with LVH have a normal coronary flow reserve and capillary density. The purpose of this study was to determine 1) whether young lambs with LVH had an abnormal response to chronotropic stress, 2) whether nonischemic mechanisms contributed to the abnormal response, and 3) whether the age at which LVH was induced affected the response. We assessed LV endomyocardial function, perfusion, and Ca(2+)-adenosinetriphosphatase (ATPase) mRNA levels in chronically instrumented lambs with and without LVH and adult sheep with and without LVH. Rapid pacing induced diastolic dysfunction, increased time constant of isovolumic relaxation using an iterative fit (tM), and elevated LV diastolic pressures in young lambs and adult sheep with LVH. During pacing, tM was greater in the adult sheep with LVH than in the young lambs with LVH. Ca(2+)-ATPase mRNA levels were 79% less in adult sheep with LVH than in those without. Ca(2+)-ATPase mRNA levels in lambs with and without LVH and adult sheep without LVH were similar. Diastolic dysfunction occurred in the absence of subendomyocardial hypoperfusion, suggesting a nonischemic mechanism. In adult sheep with LVH diastolic dysfunction was associated with a marked reduction in Ca(2+)-ATPase mRNA levels.

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