Impaired load dependence of diaphragm relaxation  during congestive heart failure in the rabbit

The load dependence (LD) of relaxation was studied in the diaphragm of rabbits with congestive heart failure (CHF). CHF ( n = 15) was induced by combined chronic volume and pressure overload. Aortic insufficiency was induced by forcing a catheter through the aortic sigmoid valves, followed 3 wk later by abdominal aortic stenosis. Six weeks after the first intervention, animals developed CHF. Sham-operated animals served as controls (C; n = 12). Diaphragm mechanics were studied in vitro on isolated strips, at 22°C, in isotonic and isometric loading conditions. Contractility was lower in the CHF group, as reflected by lower total tension: 1.11 ± 0.10 in CHF vs. 2.38 ± 0.15 N/cm2 in C in twitch ( P < 0.001) and 2.46 ± 0.22 in CHF vs. 4.90 ± 0.25 N ⋅ cm−2 in C in tetanus ( P < 0.001). The index LD was used to quantify the load dependence of relaxation: LD is <1 in load-dependent muscles and tends toward 1 in load-independent muscles. LD was significantly higher in CHF than in C rabbits, in both twitch (0.99 ± 0.01 vs. 0.75 ± 0.03; P < 0.001) and tetanus (0.95 ± 0.02 vs. 0.84 ± 0.02; P < 0.001). In the CHF rabbits’ diaphragm, the fall in total tension was linearly related to the fall in load dependence of relaxation. The decrease in load dependence of relaxation in CHF animals suggests sarcoplasmic reticulum abnormalities. Impairment of the sarcoplasmic reticulum may also partly account for the decrease in contractile performance of diaphragm in CHF animals.

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Cardiac fibroblasts acquire properties of matrifibrocytes in vitro and in mice with pressure overload-induced congestive heart failure

European Heart Journal ◽

10.1093/ehjci/ehaa946.3741 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

K.M Herum ◽

G Gilles ◽

A Romaine ◽

A.O Melleby ◽

G Christensen ◽

...

Keyword(s):

Heart Failure ◽

Congestive Heart Failure ◽

Cardiac Fibroblasts ◽

Pressure Overload ◽

Left Ventricular Pressure ◽

Left Ventricular ◽

Funding Source ◽

High Stiffness

Abstract Introduction Activation of cardiac fibroblasts (CFB) is a key step in development of fibrosis in the heart. It was recently shown that, in addition to the well-studied myofibroblast (myoFB) phenotype, activated cardiac fibroblasts can adopt a newly defined matrifibrocyte phenotype, characterized by expression of extracellular matrix (ECM) genes associated with bone, cartilage and tendon development. However, it is unknown whether matrifibrocytes exists in the pressure-overloaded fibrotic and failing heart, and whether substrate stiffness drives differentiation. Hypothesis Matrifibrocyte differentiation occurs in vitro during culturing of primary cardiac fibroblasts, and in vivo in response to left ventricular pressure overload. Methods Left ventricular pressure overload induced by o-ring aortic banding (ORAB) induced cardiac phenotypes of concentric hypertrophic remodelling and congestive heart failure. Primary CFB from adult mice were cultured on plastic or soft polyacrylamide hydrogels (4.5 kPa) for various times. mRNA expression of phenotypic markers were measured by RT-PCR. Presence of smooth muscle α-actin (SMA) fibers was determined by immunocytochemistry. Results ECM genes normally expressed in bone and cartilage (COMP, CILP-2, OPG and SCX) were upregulated in hypertrophic left ventricles of mice with congestive heart failure. The myoFB marker acta2 was increased 2 weeks after ORAB, returned to baseline at 4 weeks and increased again at 20 weeks when the left ventricle was dilating and failing, indicating that the myoFB phenotype is not permanent. In vitro, primary CFB upregulated bone/cartilage-associated ECM genes after 12 days of culturing on plastic. Acta2 mRNA and SMA protein levels peaked after 9 days in culture whereafter they declined, indicating a shift in phenotype. Culturing primary CFB on soft (4.5 kPa) hydrogels delayed, but did not prevent, myoFB differentiation while expression of bone/cartilage ECM genes was absent or low, indicating that high stiffness is a driver of the matrifibrocyte phenotype. Blockers of mechanotransduction, SB431542 (TGFβRI inhibitor), Y27623 (ROCK inhibitor) and cyclosporine A (calcineurin inhibitor), completely inhibited myoFB differentiation but upregulated several matrifibrocyte markers, indicating that distinct signaling pathways regulate myoFB and matrifibrocyte differentiation. Removing inhibitors re-induced myofibroblast markers in cells on plastic but not on soft gels consistent with high stiffness promoting myofibroblast differentiation. Conclusion Primary cardiac fibroblasts acquire characteristics of matrifibrocytes in vitro when cultured for long time on plastic and in vivo in left ventricles of mice with pressure overload-induced congestive heart failure. Funding Acknowledgement Type of funding source: Public grant(s) – EU funding. Main funding source(s): Marie Sklodowska-Curie Individual Fellowship

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Glomerular atrial natriuretic factor receptors in experimental congestive heart failure

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1993.265.3.h923 ◽

1993 ◽

Vol 265 (3) ◽

pp. H923-H928 ◽

Cited By ~ 1

Author(s):

R. Isnard ◽

A. Carayon ◽

J. Eurin ◽

G. Maistre ◽

N. Bouanani ◽

...

Keyword(s):

Heart Failure ◽

Congestive Heart Failure ◽

Atrial Natriuretic Factor ◽

Renal Response ◽

Cgmp Production ◽

Natriuretic Factor ◽

Abdominal Aortic ◽

Atrial Natriuretic

Heart failure is usually characterized by a relative insensitivity to atrial natriuretic factor (ANF). Downregulation of ANF receptors has been reported but remains controversial. Renal response to ANF infusion, glomerular ANF receptors, and guanosine 3',5'-cyclic monophosphate (cGMP) production have been studied in rabbits with congestive heart failure (CHF) after traumatic aortic regurgitation and abdominal aortic stenosis. Diuresis and natriuresis induced by ANF infusions were significantly decreased in CHF animals. Plasma cGMP was higher in CHF rabbits before ANF administration than in controls (37.6 +/- 7.2 vs. 17.1 +/- 3.9 pmol/ml, P < 0.02) and increased to a same level after ANF in both groups (48.8 +/- 4.2 vs. 52.5 +/- 2.8 pmol/ml, NS). No difference was found in glomerular ANF receptor density (436 +/- 54 vs. 425 +/- 57 fmol/mg protein, NS) nor in affinity between the two groups (dissociation constant; 240 +/- 24 vs. 347 +/- 49 pM, NS). Moreover, in vitro glomerular cGMP production in response to exogenous ANF was preserved. In conclusion, despite a blunted renal response to ANF in vivo, glomerular ANF receptors were unchanged in this model, and no defect in cGMP production in response to ANF was found. This suggests the existence of an intracellular defect beyond the second messenger.

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Congenital mitral stenosis, subvalvular aortic stenosis, and congestive heart failure in a duck

Journal of Veterinary Cardiology ◽

10.1016/j.jvc.2008.01.002 ◽

2008 ◽

Vol 10 (1) ◽

pp. 67-73 ◽

Cited By ~ 5

Author(s):

Elizabeth B. Mitchell ◽

Michelle G. Hawkins ◽

Joao S. Orvalho ◽

William P. Thomas

Keyword(s):

Heart Failure ◽

Congestive Heart Failure ◽

Aortic Stenosis ◽

Mitral Stenosis ◽

Subvalvular Aortic Stenosis ◽

Congenital Mitral Stenosis

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A novel role for miR-133a in centrally mediated activation of the renin-angiotensin system in congestive heart failure

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00721.2016 ◽

2017 ◽

Vol 312 (5) ◽

pp. H968-H979 ◽

Cited By ~ 9

Author(s):

Neeru M. Sharma ◽

Shyam S. Nandi ◽

Hong Zheng ◽

Paras K. Mishra ◽

Kaushik P. Patel

Keyword(s):

Heart Failure ◽

Congestive Heart Failure ◽

Paraventricular Nucleus ◽

Renin Angiotensin System ◽

Luciferase Reporter ◽

Mrna Levels ◽

Ang Ii ◽

Angiotensin System ◽

Renin Angiotensin

An activated renin-angiotensin system (RAS) within the central nervous system has been implicated in sympathoexcitation during various disease conditions including congestive heart failure (CHF). In particular, activation of the RAS in the paraventricular nucleus (PVN) of the hypothalamus has been recognized to augment sympathoexcitation in CHF. We observed a 2.6-fold increase in angiotensinogen (AGT) in the PVN of CHF. To elucidate the molecular mechanism for increased expression of AGT, we performed in silico analysis of the 3′-untranslated region (3′-UTR) of AGT and found a potential binding site for microRNA (miR)-133a. We hypothesized that decreased miR-133a might contribute to increased AGT in the PVN of CHF rats. Overexpression of miR-133a in NG108 cells resulted in 1.4- and 1.5-fold decreases in AGT and angiotensin type II (ANG II) type 1 receptor (AT1R) mRNA levels, respectively. A luciferase reporter assay performed on NG108 cells confirmed miR-133a binding to the 3′-UTR of AGT. Consistent with these in vitro data, we observed a 1.9-fold decrease in miR-133a expression with a concomitant increase in AGT and AT1R expression within the PVN of CHF rats. Furthermore, restoring the levels of miR-133a within the PVN of CHF rats with viral transduction resulted in a significant reduction of AGT (1.4-fold) and AT1R (1.5-fold) levels with a concomitant decrease in basal renal sympathetic nerve activity (RSNA). Restoration of miR-133a also abrogated the enhanced RSNA responses to microinjected ANG II within the PVN of CHF rats. These results reveal a novel and potentially unique role for miR-133a in the regulation of ANG II within the PVN of CHF rats, which may potentially contribute to the commonly observed sympathoexcitation in CHF. NEW & NOTEWORTHY Angiotensinogen (AGT) expression is upregulated in the paraventricular nucleus of the hypothalamus through posttranscriptional mechanism interceded by microRNA-133a in heart failure. Understanding the mechanism of increased expression of AGT in pathological conditions leading to increased sympathoexcitation may provide the basis for the possible development of new therapeutic agents with enhanced specificity.

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

Circulation Research ◽

10.1161/res.111.suppl_1.a285 ◽

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.

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Aortic Stenosis: From Pressure Overload to Heart Failure

Heart Failure Clinics ◽

10.1016/j.hfc.2006.11.001 ◽

2006 ◽

Vol 2 (4) ◽

pp. 435-442 ◽

Cited By ~ 25

Author(s):

Blase A. Carabello

Keyword(s):

Heart Failure ◽

Aortic Stenosis ◽

Pressure Overload

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Cardiac Protection of Valsartan on Juvenile Rats with Heart Failure by Inhibiting Activity of CaMKII via Attenuating Phosphorylation

BioMed Research International ◽

10.1155/2017/4150158 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7

Author(s):

Yao Wu ◽

Feifei Si ◽

Xiaojuan Ji ◽

Kunfeng Jiang ◽

Sijie Song ◽

...

Keyword(s):

Heart Failure ◽

Cardiac Myocyte ◽

Pressure Overload ◽

The Other ◽

Calcium Handling ◽

Juvenile Rats ◽

Abdominal Aortic ◽

Calcium Handling Proteins ◽

Increased Activity ◽

Induce Heart Failure

Background. This study was undertaken to determine relative contributions of phosphorylation and oxidation to the increased activity of calcium/calmodulin-stimulated protein kinase II (CaMKII) in juveniles with cardiac myocyte dysfunction due to increased pressure overload. Methods. Juvenile rats underwent abdominal aortic constriction to induce heart failure. Four weeks after surgery, rats were then randomly divided into two groups: one group given valsartan (HF + Val) and the other group given placebo (HF + PBO). Simultaneously, the sham-operated rats were randomly given valsartan (Sham + Val) or placebo (Sham + PBO). After 4 weeks of treatment, Western blot analysis was employed to quantify CaMKII and relative calcium handling proteins (RyR2 and PLN) in all groups. Results. The deteriorated cardiac function was reversed by valsartan treatment. In ventricular muscle cells of group HF + PBO, Thr287 phosphorylation of CaMKII and S2808 phosphorylation of RyR2 and PLN were increased and S16 phosphorylation of PLN was decreased compared to the other groups, while Met281 oxidation was not significantly elevated. In addition, these changes in the expression of calcium handling proteins were ameliorated by valsartan administration. Conclusions. The phosphorylation of Thr286 is associated with the early activation of CaMKII rather than the oxidation of Met281.

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

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1994.266.1.h68 ◽

1994 ◽

Vol 266 (1) ◽

pp. H68-H78 ◽

Cited By ~ 1

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.

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