Role of sarcoplasmic reticulum in loss of load-sensitive relaxation in pressure overload cardiac hypertrophy

1994 ◽  
Vol 266 (1) ◽  
pp. H68-H78 ◽  
Author(s):  
C. R. Cory ◽  
R. W. Grange ◽  
M. E. Houston
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cardiac Hypertrophy ◽  
Atpase Activity ◽  
Pressure Overload ◽  
Fold Increase ◽  
Left Ventricular ◽  
Isometric Tension ◽  
Tension Development ◽  
Sequestration Potential

The loss of load-sensitive relaxation observed in the pressure-overloaded heart may reflect a strategy of slowed cytosolic Ca2+ uptake to yield a prolongation of the active state of the muscle and a decrease in cellular energy expenditure. A decrease in the potential of the sarcoplasmic reticulum (SR) to resequester cytosolic Ca2+ during diastole could contribute to this attenuated load sensitivity. To test this hypothesis, both in vitro mechanical function of anterior papillary muscles and the SR Ca2+ sequestration potential of female guinea pig left ventricle were compared in cardiac hypertrophy (Hyp) and sham-operated (Sham) groups. Twenty-one days of pressure overload induced by coarctation of the suprarenal, subdiaphragmatic aorta resulted in a 36% increase in left ventricular mass in the Hyp. Peak isometric tension, the rate of isometric tension development, and the maximal rates of isometric and isotonic relaxation were significantly reduced in Hyp. Load-sensitive relaxation were significantly reduced in Hyp. Load-sensitive relaxation quantified by the ratio of a rapid loading to unloading force step in isotonically contracting papillary muscle was reduced 50% in Hyp muscles. Maximum activity of SR Ca(2+)-adenosinetriphosphatase (ATPase) measured under optimal conditions (37 degrees C; saturating Ca2+) was unaltered, but at low free Ca2+ concentrations (0.65 microM), it was decreased by 43% of the Sham response. Bivariate regression analysis revealed a significant (r = 0.84; P = 0.009) relationship between the decrease in SR Ca(2+)-ATPase activity and the loss of load-sensitive relaxation after aortic coarctation. Stimulation of the SR Ca(2+)-ATPase by the catalytic subunit of adenosine 3',5'-cyclic monophosphate-dependent protein kinase resulted in a 2.6-fold increase for Sham but only a 1.6-fold increase for Hyp. Semiquantitative Western blot radioimmunoassays revealed that the changes in SR Ca(2+)-ATPase activity were not due to decreases in the content of the Ca(2+)-ATPase protein or phospholamban. Our data directly implicate a role for decreased SR function in attenuated load sensitivity. A purposeful downregulation of SR Ca2+ uptake likely results from a qualitative rather than a quantitative change in the ATPase and possibly one of its key regulators, phospholamban.

Myocardial mechanics predict hemodynamic performance during normal function and alcohol-induced dysfunction in rats

1991 ◽  
Vol 261 (6) ◽  
pp. H1880-H1888
Author(s):  
J. M. Capasso ◽  
P. Li ◽  
P. Anversa
Keyword(s):  
Pressure Rise ◽  
Normal Function ◽  
Left Ventricular ◽  
Isometric Tension ◽  
Papillary Muscles ◽  
Least Squares Regression ◽  
Tension Development ◽  
Myocardial Mechanics

To determine whether mechanical evaluation of muscle tissue removed from the myocardium can be employed as a direct indicator of cardiac contractile performance in situ, isometric and isotonic parameters of muscle mechanics in vitro were correlated with in vivo global functional characteristics of the same heart. Twelve-month-old animals maintained on standard food and water were employed as representative of normal cardiac function. Animals of identical age with left ventricular (LV) dysfunction induced by oral alcohol (30%) ingestion from 4 to 12 mo were utilized to represent depressed cardiac performance. Accordingly, 24 h after the establishment of the hemodynamic profile for a control or experimental heart, the LV posterior papillary muscle was removed from the same heart and examined isometrically and isotonically. Least squares regression analysis was employed to establish a correlation coefficient and P values between various in vitro and in vivo parameters. Hemodynamic measurements were performed under chloral hydrate anesthesia and LV pump performance was evaluated with respect to aortic and ventricular pressures and the rates of rise and decay of the LV pressure trace. Papillary muscles were evaluated with respect to timing parameters of the isometric and isotonic twitch, the first derivative of isometric tension development, and the speed of muscle shortening at increasing physiologic loads. LV peak rate of pressure rise and decay were then correlated with the various isometric and isotonic properties. Myocardial mechanics and hemodynamics revealed depressed function in the papillary muscles and hearts from alcoholic rats. Moreover, significant correlations were found between the LV rate of pressure change (peak +dP/dt and -dP/dt) and both isometric and isotonic twitch measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of SIRT1 by Resveratrol Alleviates Pressure Overload-Induced Cardiac Hypertrophy via Suppression of TGF-β1 Signaling

Pharmacology ◽  
2021 ◽  
pp. 1-15
Author(s):  
Yong Chen ◽  
Ting He ◽  
Zhongjun Zhang ◽  
Junzhi Zhang
Keyword(s):  
Cardiac Hypertrophy ◽  
Protective Effect ◽  
Signaling Pathway ◽  
Cardiac Fibrosis ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Neonatal Rat ◽  
Ang Ii ◽  
Tgf Β1

<b><i>Introduction:</i></b> Silent information regulator 1 (SIRT1) has been extensively investigated in the cardiovascular system and has been shown to play a pivotal role in mediating cell death/survival, energy production, and oxidative stress. However, the functional role of SIRT1 in pressure overload-induced cardiac hypertrophy and dysfunction remains unclear. Resveratrol (Rsv), a widely used activator of SIRT1, has been reported to protect against cardiovascular disease. We here examine whether activation of SIRT1 by Rsv attenuate pressure overload-induced cardiac hypertrophy and to identify the underlying molecular mechanisms. <b><i>Methods:</i></b> In vivo, rat model of pressure overload-induced myocardial hypertrophy was established by abdominal aorta constriction (AAC) procedure. In vitro, Angiotensin II (Ang II) was applied to induce hypertrophy in cultured neonatal rat cardiomyocytes (NCMs). Hemodynamics and histological analyses of the heart were evaluated. The expression of SIRT1, transforming growth factor-β1 (TGF-β1)/phosphorylated (p)-small mother against decapentaplegic (Smad)3 and hypertrophic markers were determined by immunofluorescence, real-time PCR, and Western blotting techniques. <b><i>Results:</i></b> In the current study, Rsv treatment improved left ventricular function and reduced left ventricular hypertrophy and cardiac fibrosis significantly in the pressure overload rats. The expression of SIRT1 was significantly reduced, while the expression of TGF-β1/p-Smad3 was significantly enhanced in AAC afflicted rat heart. Strikingly, treatment with Rsv restored the expressions of SIRT1 and TGF-β1/p-Smad3 under AAC influence. However, SIRT1 inhibitor Sirtinol (Snl) markedly prevented the effects of Rsv, which suggest that SIRT1 signaling pathway was involved in the cardiac protective effect of Rsv. In vitro studies performed in Ang II-induced hypertrophy in NCMs confirmed the cardiac protective effect of Rsv. Furthermore, the study presented that SIRT1 negatively correlated with the cardiac hypertrophy, cardiac fibrosis, and the TGF-β1/p-Smad3 expression. <b><i>Conclusions:</i></b> Taken together, these results indicated that activation of SIRT1 by Rsv attenuates cardiac hypertrophy, cardiac fibrosis, and improves cardiac function possibly via regulation of the TGF-β1/p-Smad3 signaling pathway. Our study may provide a potential therapeutic strategy for cardiac hypertrophy.

Alterations in sarcoplasmic reticulum calcium-storing proteins in pressure-overload cardiac hypertrophy

1997 ◽  
Vol 272 (1) ◽  
pp. H168-H175 ◽  
Author(s):  
H. Tsutsui ◽  
Y. Ishibashi ◽  
K. Imanaka-Yoshida ◽  
S. Yamamoto ◽  
T. Yoshida ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cardiac Hypertrophy ◽  
Protein Level ◽  
Contractile Function ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Regulatory Proteins ◽  
Control Value ◽  
Abdominal Aortic ◽  
Hypertrophied Myocardium

The alterations of intracellular calcium (Ca2+) homeostasis may be responsible for the contractile defects in pressure-overload cardiac hypertrophy. The Ca(2+)-adenosinetriphosphatase (ATPase) protein level of the sarcoplasmic reticulum (SR) is reduced in the hypertrophied or failing heart. However, it is not known whether Ca(2+)-storing proteins, including calsequestrin and calreticulin, are also altered during cardiac hypertrophy. We quantified SR Ca(2+)-regulatory proteins using Western blot analysis in left ventricular (LV) muscle isolated from sham-operated control rats (n = 6) and rats with pressure overload 4 wk after abdominal aortic constriction (n = 7). The contractile function of isolated LV myocytes, assessed by the sarcomere motion measured with laser diffraction, was depressed in aortic-constricted rats. The SR Ca(2+)-ATPase protein level was decreased to 56 +/- 9% (SE) of the control value in hypertrophied myocardium (P < 0.01). The calsequestrin protein level was not altered, whereas calreticulin was increased by 120 +/- 3% of the control value in aortic-constricted rats (P < 0.05). The alterations in SR Ca(2+)-regulatory proteins were equally observed in hypertrophied hearts even when the results were normalized using the amounts of myosin heavy chain proteins in each sample. Immunohistochemical staining of calsequestrin in the control heart showed cross striations at the Z lines, whereas calreticulin was hardly observed within myocytes but was intense within interstitial fibroblasts. In the hypertrophied heart, calreticulin was observed at the perinuclear region within the myocyte cytoplasm. These data indicate that pressure-overload cardiac hypertrophy causes the alterations in SR Ca(2+)-storing proteins as well as in Ca(2+)-ATPase, which may contribute to the contractile dysfunction of the hypertrophied myocytes.

Abstract P478: Farnesyl Transferase Inhibitor Tipifarnib Reduces Circulating Exosomes And Protects Against Pressure Overload-mediated Cardiac Hypertrophy

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Vandana Mallaredy
Keyword(s):  
Heart Failure ◽  
Cardiac Hypertrophy ◽  
Cardiac Remodeling ◽  
Molecular Mechanisms ◽  
Cell Communication ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Farnesyl Transferase ◽  
Farnesyl Transferase Inhibitor

Clinically, Hypertrophic cardiomyopathy (HCM) in response to pathophysiological stress is one of the major initiating factors for the onset of cardiac remodeling leading to heart failure. Studies have revealed that HCM characterized by left ventricular hypertrophy, hypercontractility, and impaired relaxation is mainly driven by an intricate crosstalk among the multiple cellular and molecular mechanisms, which leads to heart failure. In agreement with this observation, we investigated if the Tipifarnib-mediated reduction/alteration of circulating exosomes mediates cardiac cell communication during HCM. Several studies have shown Tipifarnib as a potential Farnesyl transferase inhibitor. However, in recent past Tipifarnib has been shown to target exosomes biogenesis by several mechanisms such as inhibiting Ras pathway, ESCRT complex etc. Tipifarnib treatment in mice significantly reduced the number of circulating plasma exosomes. We examined the response of Tipifarnib treatment (10 mg/kg body weight) in C57BL6J male mice subjected to transverse aortic constriction (TAC) surgery. Untreated TAC mice had worsening of systolic Left Ventricular function at 4 weeks that further deteriorated at 8 weeks, while the treatment with Tipifarnib substantially improved cardiac functions by reducing cardiac hypertrophy and fibrosis. Exosomes isolated from the serum of sham and TAC mice with or without tipifarnib were used for in vitro cell based analyses. We observed that the exosomes isolated from Tipifarnib treated TAC mice reduced isoproterenol (ISO)-induced cardiomyoblast hypertrophy and fibrosis-associated genes in adult cardiac fibroblasts. Taken together, our studies suggest Tipifarnib protects against pressure overload induced cardiac remodeling and dysfunction by altering hypertrophic and fibrotic gene expression, by potentially reducing circulating exosomes or by altering exosome contents. Ongoing studies will clarify the molecular mechanisms of these observations.

scholarly journals Cellular Interplay and Cytokine Hierarchy Cause Pathological Cardiac Hypertrophy in RAF1-Mutant Noonan Syndrome

2017 ◽  
Author(s):  
Jiani C. Yin ◽  
Mathew J. Platt ◽  
Xixi Tian ◽  
Xue Wu ◽  
Peter H. Backx ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Noonan Syndrome ◽  
Cardiac Contractility ◽  
Pressure Overload ◽  
Neutralizing Antibody ◽  
Cell Types ◽  
Left Ventricular ◽  
Cardiomyocyte Hypertrophy

AbstractNoonan syndrome (NS) is caused by mutations in RAS/ERK pathway genes, and is characterized by craniofacial, growth, cognitive and cardiac defects. NS patients with kinase-activating RAF1 alleles typically develop pathological left ventricular hypertrophy (LVH), which is reproduced in Raf1L613V/+ knock-in mice. Here, using inducible Raf1L613V expression, we show that LVH results from the interplay of cardiac cell types. Cardiomyocyte Raf1L613V enhances Ca2+ sensitivity and cardiac contractility without causing hypertrophy. Raf1L613V expression in cardiomyocytes or activated fibroblasts exacerbates pressure overload-evoked fibrosis. Endothelial/endocardial (EC) Raf1L613V causes cardiac hypertrophy without affecting contractility. Co-culture and neutralizing antibody experiments reveal a cytokine (TNF/IL6) hierarchy in Raf1L613V-expressing ECs that drives cardiomyocyte hypertrophy in vitro. Furthermore, post-natal TNF inhibition normalizes the increased wall thickness and cardiomyocyte hypertrophy in vivo. We conclude that NS cardiomyopathy involves cardiomyocytes, ECs, and fibroblasts, TNF/IL6 signaling components represent potential therapeutic targets, and abnormal EC signaling might contribute to other forms of LVH.

Abstract 285: Cardiac Inflammation and Fibrosis Induced by Heart Failure Are Reversed by Short-Duration Estrogen Therapy

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Andrea Iorga ◽  
Rangarajan Nadadur ◽  
Salil Sharma ◽  
Jingyuan Li ◽  
Mansoureh Eghbali
Keyword(s):  
Heart Failure ◽  
Estrogen Therapy ◽  
Pressure Overload ◽  
Decompensated Heart Failure ◽  
Left Ventricular ◽  
Neonatal Rat ◽  
In Vivo Model ◽  
Anti Inflammatory

Heart failure is generally characterized by increased fibrosis and inflammation, which leads to functional and contractile defects. We have previously shown that short-term estrogen (E2) treatment can rescue pressure overload-induced decompensated heart failure (HF) in mice. Here, we investigate the anti-inflammatory and anti-fibrotic effects of E2 on reversing the adverse remodeling of the left ventricle which occurs during the progression to heart failure. Trans-aortic constriction procedure was used to induce HF. Once the ejection fraction reached ∼30%, one group of mice was sacrificed and the other group was treated with E2 (30 αg/kg/day) for 10 days. In vitro, co-cultured neonatal rat ventricular myocytes and fibroblasts were treated with Angiotensin II (AngII) to simulate cardiac stress, both in the presence or absence of E2. In vivo RT-PCR showed that the transcript levels of the pro-fibrotic markers Collagen I, TGFβ, Fibrosin 1 (FBRS) and Lysil Oxidase (LOX) were significantly upregulated in HF (from 1.00±0.16 to 1.83±0.11 for Collagen 1, 1±0.86 to 4.33±0.59 for TGFβ, 1±0.52 to 3.61±0.22 for FBRS and 1.00±0.33 to 2.88±0.32 for LOX) and were reduced with E2 treatment to levels similar to CTRL. E2 also restored in vitro AngII-induced upregulation of LOX, TGFβ and Collagen 1 (LOX:1±0.23 in CTRL, 6.87±0.26 in AngII and 2.80±1.5 in AngII+E2; TGFβ: 1±0.08 in CTRL, 3.30±0.25 in AngII and 1.59±0.21 in AngII+E2; Collagen 1: 1±0.05 in CTRL.2±0.01 in AngII and 0.65±0.02 (p<0.05, values normalized to CTRL)). Furthermore, the pro-inflammatory interleukins IL-1β and IL-6 were upregulated from 1±0.19 to 1.90±0.09 and 1±0.30 to 5.29±0.77 in the in vivo model of HF, respectively, and reversed to CTRL levels with E2 therapy. In vitro, IL-1β was also significantly increased ∼ 4 fold from 1±0.63 in CTRL to 3.86±0.14 with AngII treatment and restored to 1.29±0.77 with Ang+E2 treatment. Lastly, the anti-inflammatory interleukin IL-10 was downregulated from 1.00±0.17 to 0.49±0.03 in HF and reversed to 0.67±0.09 in vivo with E2 therapy (all values normalized to CTRL). This data strongly suggests that one of the mechanisms for the beneficial action of estrogen on left ventricular heart failure is through reversal of inflammation and fibrosis.

Abstract 1770: Proteasome Switching is Associated with Adverse Cardiac Remodeling in a Transgenic Mouse Model of Sustained Inflammatory Signaling

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Wei Wang ◽  
Gabor Szalai ◽  
Natarajan Sivasubramanian ◽  
Douglas L Mann
Keyword(s):  
Proteolytic Activity ◽  
Cardiac Remodeling ◽  
Fold Increase ◽  
Left Ventricular ◽  
26S Proteasome ◽  
Myocardial Inflammation ◽  
Fluorescent Substrate ◽  
Lv Remodeling ◽  
Apoptotic Proteins

The 26S proteasome possess proteolytic activity and deubiquitinating (DUB) activity of ubiquitin tagged proteins. Whereas the proteolytic activity of the 26S proteasome facilitates protein degradation, proteasome DUB activity spares proteins from degradation by shortening the length of the ubiquitin chains, thereby preventing proteins from being degraded by the 26S proteasome. In yeast, increased DUB activity is beneficial by preventing depletion of ubiquitin pools critical for cell signaling. However, the role of DUB activity in mammalian systems is not known. We have shown that mice with cardiac restricted overexpression of tumor necrosis factor (sTNF mice) develop a heart failure phenotype characterized by progressive left ventricular (LV) remodeling and accumulation of pro-apoptotic proteins, including Smac/Diablo. To determine whether the adverse LV remodeling in sTNF mice was related to alterations in DUB activity we measured the cleavage of ubiquitin-AMC, an in vitro fluorescent substrate for DUBs, in purified preparations of the 26S proteasome obtained from hearts of 4 week old sTNF and littermate (LM) control mice. Compared to LM controls we observed a significant (p < 0.001) 60.8% decrease in activity of the 26S proteasome and a significant (p < 0.01) 24.2% increase in DUB activity in sTNF mouse hearts. There was also a significant (p < 0.01) 11-fold increase myocardial protein levels of USP14, a critical DUB associated with the 26S proteasome in sTNF mouse hearts. The decrease in 26S proteasome activity and increased DUB activity in sTNF mouse hearts was accompanied by an increase in myocardial levels of ubiquitinated SMAC/Diablo. Taken together these results show for the first time that sustained myocardial inflammation leads to switch in the function of the proteasome from a proteolytic function to a protein sparing function. Although this “proteasome switching” may provide a short-term adaptive benefit by preventing depletion of critical ubiquitin pools, it may lead to long-term maladaptive consequences by allowing the progressive accumulation of potentially harmful pro-apoptotic proteins in the cytosol, which may in turn promote programmed cell death and adverse cardiac remodeling.

scholarly journals Bakuchiol protects against pathological cardiac hypertrophy by blocking NF-κB signaling pathway

2018 ◽  
Vol 38 (5) ◽  
Author(s):  
Zheng Wang ◽  
Lu Gao ◽  
Lili Xiao ◽  
Lingyao Kong ◽  
Huiting Shi ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Signaling Pathway ◽  
Pressure Overload ◽  
Neonatal Rat ◽  
Oral Gavage ◽  
Aortic Banding ◽  
Rat Cardiomyocytes ◽  
Pathological Cardiac Hypertrophy ◽  
First Time

Bakuchiol (Bak), a monoterpene phenol isolated from the seeds of Psoralea corylifolia, has been widely used to treat a large variety of diseases in both Indian and Chinese folkloric medicine. However, the effects of Bak on cardiac hypertrophy remain unclear. Therefore, the present study was designed to determine whether Bak could alleviate cardiac hypertrophy. Mice were subjected to aortic banding (AB) to induce cardiac hypertrophy model. Bak of 1 ml/100 g body weight was given by oral gavage once a day from 1 to 8 weeks after surgery. Our data demonstrated for the first time that Bak could attenuate pressure overload-induced cardiac hypertrophy and could attenuate fibrosis and the inflammatory response induced by AB. The results further revealed that the effect of Bak on cardiac hypertrophy was mediated by blocking the activation of the NF-κB signaling pathway. In vitro studies performed in neonatal rat cardiomyocytes further proved that the protective effect of Bak on cardiac hypertrophy is largely dependent on the NF-κB pathway. Based on our results, Bak shows profound potential for its application in the treatment of pathological cardiac hypertrophy, and we believe that Bak may be a promising therapeutic candidate to treat cardiac hypertrophy and heart failure.

scholarly journals Piezo1-Mediated Mechanotransduction Promotes Cardiac Hypertrophy by Impairing Calcium Homeostasis to Activate Calpain/Calcineurin Signaling

Hypertension ◽  
2021 ◽  
Author(s):  
Yuhao Zhang ◽  
Sheng-an Su ◽  
Wudi Li ◽  
Yuankun Ma ◽  
Jian Shen ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Ion Channel ◽  
Calcium Homeostasis ◽  
Pressure Overload ◽  
Cell Physiology ◽  
Hypertrophic Growth ◽  
Molecular Features ◽  
Mechanosensitive Ion Channel

Hemodynamic overload induces pathological cardiac hypertrophy, which is an independent risk factor for intractable heart failure in long run. Beyond neurohumoral regulation, mechanotransduction has been recently recognized as a major regulator of cardiac hypertrophy under a myriad of conditions. However, the identification and molecular features of mechanotransducer on cardiomyocytes are largely sparse. For the first time, we identified Piezo1 (Piezo type mechanosensitive ion channel component 1), a novel mechanosensitive ion channel with preference to Ca 2+ was remarkably upregulated under pressure overload and enriched near T-tubule and intercalated disc of cardiomyocyte. By applying cardiac conditional Piezo1 knockout mice (Piezo1 fl/fl Myh6Cre+, Piezo1 Cko ) undergoing transverse aortic constriction, we demonstrated that Piezo1 was required for the development of cardiac hypertrophy and subsequent adverse remodeling. Activation of Piezo1 by external mechanical stretch or agonist Yoda1 lead to the enlargement of cardiomyocytes in vitro, which was blocked by Piezo1 silencing or Yoda1 analog Dooku1 or Piezo1 inhibitor GsMTx4. Mechanistically, Piezo1 perturbed calcium homeostasis, mediating extracellular Ca 2+ influx and intracellular Ca 2+ overload, thereby increased the activation of Ca 2+ -dependent signaling, calcineurin, and calpain. Inhibition of calcineurin or calpain could abolished Yoda1 induced upregulation of hypertrophy markers and the hypertrophic growth of cardiomyocytes in vitro. From a comprehensive view of the cardiac transcriptome, most of Piezo1 affected genes were highly enriched in muscle cell physiology, tight junction, and corresponding signaling. This study characterizes an undefined role of Piezo1 in pressure overload induced cardiac hypertrophy. It may partially decipher the differential role of calcium under pathophysiological condition, implying a promising therapeutic target for cardiac dysfunction.

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