scholarly journals Loss of Rad-GTPase produces a novel adaptive cardiac phenotype resistant to systolic decline with aging

2015 ◽  
Vol 309 (8) ◽  
pp. H1336-H1345 ◽  
Author(s):  
Janet R. Manning ◽  
Catherine N. Withers ◽  
Bryana Levitan ◽  
Jeffrey D. Smith ◽  
Douglas A. Andres ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Output ◽  
Calcium Current ◽  
Ventricular Myocytes ◽  
Morphological Changes ◽  
Heart Function ◽  
Early Time ◽  
Cardiac Phenotype ◽  
Systolic And Diastolic Function

Rad-GTPase is a regulator of L-type calcium current (LTCC), with increased calcium current observed in Rad knockout models. While mouse models that result in elevated LTCC have been associated with heart failure, our laboratory and others observe a hypercontractile phenotype with enhanced calcium homeostasis in Rad−/−. It is currently unclear whether this observation represents an early time point in a decompensatory progression towards heart failure or whether Rad loss drives a novel phenotype with stable enhanced function. We test the hypothesis that Rad−/− drives a stable nonfailing hypercontractile phenotype in adult hearts, and we examine compensatory regulation of sarcoplasmic reticulum (SR) loading and protein changes. Heart function was measured in vivo with echocardiography. In vivo heart function was significantly improved in adult Rad−/− hearts compared with wild type. Heart wall dimensions were significantly increased, while heart size was decreased, and cardiac output was not changed. Cardiac function was maintained through 18 mo of age with no decompensation. SR releasable Ca2+ was increased in isolated Rad−/− ventricular myocytes. Higher Ca2+ load was accompanied by sarco/endoplasmic reticulum Ca2+ ATPase 2a (SERCA2a) protein elevation as determined by immunoblotting and a rightward shift in the thapsigargan inhibitor-response curve. Rad−/− promotes morphological changes accompanied by a stable increase in contractility with aging and preserved cardiac output. The Rad−/− phenotype is marked by enhanced systolic and diastolic function with increased SR uptake, which is consistent with a model that does not progress into heart failure.

Chronic receptor-mediated activation of Gi/o proteins alters basal t-tubular and sarcolemmal L-type Ca2+ channel activity through phosphatases in heart failure

2012 ◽  
Vol 302 (8) ◽  
pp. H1645-H1654 ◽  
Author(s):  
Toshihide Kashihara ◽  
Tsutomu Nakada ◽  
Hisashi Shimojo ◽  
Miwa Horiuchi-Hirose ◽  
Simmon Gomi ◽  
...  
Keyword(s):  
Heart Failure ◽  
Current Density ◽  
Ventricular Myocytes ◽  
Heterotrimeric G Proteins ◽  
Channel Activity ◽  
Open Probability ◽  
Current Densities ◽  
Fractional Shortening ◽  
Pp2a Inhibitor

L-type Ca2+ channels (LTCCs) play an essential role in the excitation-contraction coupling of ventricular myocytes. We previously found that t-tubular (TT) LTCC current density was halved by the activation of protein phosphatase (PP)1 and/or PP2A, whereas surface sarcolemmal (SS) LTCC current density was increased by the inhibition of PP1 and/or PP2A activity in failing ventricular myocytes of mice chronically treated with isoproterenol (ISO mice). In the present study, we examined the possible involvement of inhibitory heterotrimeric G proteins (Gi/o) in these abnormalities by chronically administrating pertussis toxin (PTX) to ISO mice (ISO + PTX mice). Compared with ISO mice, ISO + PTX mice exhibited significantly higher fractional shortening of the left ventricle. The expression level of Gαi2 proteins was not altered by the treatment of mice with ISO and/or PTX. ISO + PTX myocytes had normal TT and SS LTCC current densities because they had higher and lower availability and/or open probability of TT and SS LTCCs than ISO myocytes, respectively. A selective PKA inhibitor, H-89, did not affect LTCC current densities in ISO + PTX myocytes. A selective PP2A inhibitor, fostriecin, did not affect SS or TT current density in control or ISO + PTX myocytes but significantly increased TT but not SS LTCC current density in ISO myocytes. These results indicate that chronic receptor-mediated activation of Gi/o in vivo decreases basal TT LTCC activity by activating PP2A and increases basal SS LTCC activity by inhibiting PP1 without modulating PKA in heart failure.

Abstract 131: C-kit+ Cells Generated From Failed Heart Do Not Improve Failed Heart Function

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Liudmila Zakharova ◽  
Hikmet Nural ◽  
James R Nimlos ◽  
Snjezana Popovic ◽  
Lorraine Feehery ◽  
...  
Keyword(s):  
Heart Failure ◽  
Left Ventricle ◽  
Diastolic Pressure ◽  
Heart Function ◽  
Smooth Muscle Actin ◽  
Functional Improvement ◽  
Gene Expressions ◽  
Coronary Vein ◽  
Mesenchymal Transition

A pilot clinical study using autologous c-Kit+ cells showed improvement in cardiac functions in congestive heart failure (CHF), however, it is unclear if c-Kit+ cells isolated from CHF hearts are equally as potent as cells from controls. To test the potency of CHF c-Kit+ cells, myocardial infarction (MI) was created by permanent ligation of the left anterior descending coronary artery. Six weeks after MI, animals with left ventricle end-diastolic pressure (LVEDP) ≥20 mmHg and scar size ≥30% of left ventricle (LV) were designated as CHF rats. We found that CHF atrial explants generated less c-Kit+ cells compared to shams (15.7% vs. 11% sham vs. CHF). CHF c-Kit+ cells exhibited elevated levels of epicardial to mesenchymal transition markers, including Snail (2.5 fold) and Pai1 (3 fold), while the expression level of epithelial marker, E-cadherin was 3 fold lower in CHF c-Kit+ cells. Moreover, CHF c-Kit+ cells exhibited reduced gene expressions of pluripotency markers; 2.1 fold decrease in Nanog and 4.5 fold decrease in Sox 2 compared to sham cells. To evaluate the potency of the c-Kit+ cells, 1 x 10 6 cells isolated from CHFs or shams were delivered to 3 weeks post-MI CHF hearts. Cells were pre-labeled with GFP to enable their tracing in vivo and delivered to the infarcted myocardium via left coronary vein by a retrograde coronary sinus cell infusion (RCI). RCI delivery resulted in a cell distribution of LV (30%), right atrium (30%) and right ventricle (20%), while only 10% of cells were found in a left atrium. Three weeks after cells delivery, rats transplanted with sham c-Kit+ cells showed improved LVEDP (29.4 ± 6 vs. 11.7 ± 3.5 mmHg, CHF vs. CHF+ sham c-Kit+ cells) and a rise in peak rate of pressure (dPdt max) (3988 ± 520 vs. 5333 ± 597 mmHg/s). In contrast, no functional improvement was detected in rats transplanted with CHF c-Kit+ cells. Histological analysis demonstrated that transplanted c-Kit+/GFP+ cells were mostly incorporated into blood vessels and co-localized with endothelial marker vWf, and α-smooth muscle actin. Our results showed that left coronary vein is an efficient route for c-Kit+ cell delivery and that c-Kit+ cells isolated from CHF rats are less potent when transplanted in chronic heart failure rat model compared to those isolated from control.

Cellular and functional defects in a mouse model of heart failure

2000 ◽  
Vol 279 (6) ◽  
pp. H3101-H3112 ◽  
Author(s):  
Giovanni Esposito ◽  
L. F. Santana ◽  
Keith Dilly ◽  
Jader Dos Santos Cruz ◽  
Lan Mao ◽  
...  
Keyword(s):  
Heart Failure ◽  
Adrenergic Receptor ◽  
Heart Function ◽  
Imaging Techniques ◽  
Single Cells ◽  
Structural Protein ◽  
Muscle Lim Protein ◽  
Intracellular Ca ◽  
Whole Heart

Heart failure and dilated cardiomyopathy develop in mice that lack the muscle LIM protein (MLP) gene (MLP−/−). The character and extent of the heart failure that occurs in MLP−/− mice were investigated using echocardiography and in vivo pressure-volume (P-V) loop measurements. P-V loop data were obtained with a new method for mice (sonomicrometry) using two pairs of orthogonal piezoelectric crystals implanted in the endocardial wall. Sonomicrometry revealed right-shifted P-V loops in MLP−/−mice, depressed systolic contractility, and additional evidence of heart failure. Cellular changes in MLP−/− mice were examined in isolated single cells using patch-clamp and confocal Ca2+ concentration ([Ca2+]) imaging techniques. This cellular investigation revealed unchanged Ca2+ currents and Ca2+ spark characteristics but decreased intracellular [Ca2+] transients and contractile responses and a defect in excitation-contraction coupling. Normal cellular and whole heart function was restored in MLP−/− mice that express a cardiac-targeted transgene, which blocks the function of β-adrenergic receptor (β-AR) kinase-1 (βARK1). These data suggest that, despite the persistent stimulus to develop heart failure in MLP−/− mice (i.e., loss of the structural protein MLP), downregulation and desensitization of the β-ARs may play a pivotal role in the pathogenesis. Furthermore, this work suggests that the inhibition of βARK1 action may prove an effective therapy for heart failure.

scholarly journals Physical Activity and Inhibition of ACE Additively Modulate ACE/ACE-2 Balance in Heart Failure in Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Urszula Tyrankiewicz ◽  
Mariola Olkowicz ◽  
Piotr Berkowicz ◽  
Magdalena Jablonska ◽  
Ryszard T. Smolenski ◽  
...  
Keyword(s):  
Physical Activity ◽  
Heart Failure ◽  
Heart Function ◽  
Combined Treatment ◽  
Training Group ◽  
Cardiac Performance ◽  
Angiotensin Converting Enzyme Inhibition ◽  
Ang Ii ◽  
Spontaneous Physical Activity

Angiotensin-converting enzyme inhibition (ACE-I) and physical activity favorably modulate the ACE/ACE-2 balance. However, it is not clear whether physical activity and ACE-I could synergistically modulate ACE/ACE-2 balance in the course of heart failure (HF). Here, we studied the effects of combined spontaneous physical activity and ACE-I–based treatment on angiotensin (Ang) pattern and cardiac function in a mouse model of HF (Tgαq*44). Tgαq*44 mice with advanced HF (at the age of 12 months) were running spontaneously in a running wheel (exercise training group, ExT) and/or were treated with ACE inhibitor (ACE-I, perindopril, 10 mg/kg) for 2 months. Angiotensin profile was characterized by an LC-MS/MS-based method. The cardiac performance was assessed in vivo by MRI. Ang-(1–7)/Ang II ratio in both plasma and the aorta was significantly higher in the combined treatment group than the ACE-I group or ExT alone, suggesting the additive favorable effects on ACE-2/Ang-(1–7) and ACE/Ang II axes’ balance induced by a combination of ACE-I with ExT. The basal cardiac performance did not differ among the experimental groups of Tgαq*44 mice. We demonstrated additive changes in ACE/ACE-2 balance in both plasma and the aorta by spontaneous physical activity and ACE-I treatment in Tgαq*44 mice. However, these changes did not result in an improvement of failing heart function most likely because the disease was at the end-stage. Ang-(1–7)/Ang II balance represents a valuable biochemical end point for monitoring therapeutic intervention outcome in heart failure.

Influence of long-chain acylcarnitines on voltage-dependent calcium current in adult ventricular myocytes

1992 ◽  
Vol 263 (2) ◽  
pp. H410-H417 ◽  
Author(s):  
J. Wu ◽  
P. B. Corr
Keyword(s):  
Calcium Current ◽  
Ventricular Myocytes ◽  
Indirect Evidence ◽  
Cell Voltage ◽  
Time Dependent ◽  
Similar Degree ◽  
Tetraacetic Acid ◽  
Voltage Dependent ◽  
Long Chain

Long-chain acylcarnitines (LCAC) increase 3.5-fold within 2 min in ischemic myocardium in vivo, and previous studies have suggested, through indirect evidence, that LCAC can stimulate the voltage-dependent L-type Ca2+ current [ICa(L)] in both cardiac and smooth muscle cells. In the present study, whole cell voltage-clamp procedures were performed in isolated adult guinea pig ventricular myocytes to assess the direct effect of LCAC on ICa(L). The intracellular solution contained (in mM) 80 CsCl, 40 K-aspartic acid, and 5 ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). Maximal current density of ICa(L) at 0 mV was 10.1 +/- 0.5 pA/pF (n = 22) at extracellular Ca2+ concentration ([Ca2+]o) = 2.7 mM. LCAC induced a concentration (1-25 microM, n = 23)- and time-dependent, reversible decrease in ICa(L). When delivered extracellularly for 10 min, LCAC (5 microM) inhibited the maximal current of ICa(L) by 48.1 +/- 1.3% (n = 9, P less than 0.01) and shifted the half-maximal voltage of steady-state activation and inactivation from -13.1 +/- 0.5 to -6.8 +/- 0.4 mV (n = 4; P less than 0.05) and from -21.8 +/- 0.2 to -16.5 +/- 0.6 mV (n = 4; P less than 0.01), respectively. Intracellular delivery of LCAC (5 microM) also suppressed ICa(L) to a similar degree (47.5 +/- 1.5%, n = 4; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals CXCR4 Cardiac Specific Knockout Mice Develop a Progressive Cardiomyopathy

2019 ◽  
Vol 20 (9) ◽  
pp. 2267 ◽  
Author(s):  
Thomas J. LaRocca ◽  
Perry Altman ◽  
Andrew A. Jarrah ◽  
Ron Gordon ◽  
Edward Wang ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Hypertrophy ◽  
Cardiac Myocytes ◽  
Knockout Mice ◽  
Cardiac Dysfunction ◽  
Left Ventricular ◽  
Subsequent Increase ◽  
Transition Electron Microscopy ◽  
Cardiac Phenotype

Activation of multiple pathways is associated with cardiac hypertrophy and heart failure. We previously published that CXCR4 negatively regulates β-adrenergic receptor (β-AR) signaling and ultimately limits β-adrenergic diastolic (Ca2+) accumulation in cardiac myocytes. In isolated adult rat cardiac myocytes; CXCL12 treatment prevented isoproterenol-induced hypertrophy and interrupted the calcineurin/NFAT pathway. Moreover; cardiac specific CXCR4 knockout mice show significant hypertrophy and develop cardiac dysfunction in response to chronic catecholamine exposure in an isoproterenol-induced (ISO) heart failure model. We set this study to determine the structural and functional consequences of CXCR4 myocardial knockout in the absence of exogenous stress. Cardiac phenotype and function were examined using (1) gated cardiac magnetic resonance imaging (MRI); (2) terminal cardiac catheterization with in vivo hemodynamics; (3) histological analysis of left ventricular (LV) cardiomyocyte dimension; fibrosis; and; (4) transition electron microscopy at 2-; 6- and 12-months of age to determine the regulatory role of CXCR4 in cardiomyopathy. Cardiomyocyte specific-CXCR4 knockout (CXCR4 cKO) mice demonstrate a progressive cardiac dysfunction leading to cardiac failure by 12-months of age. Histological assessments of CXCR4 cKO at 6-months of age revealed significant tissue fibrosis in knockout mice versus wild-type. The expression of atrial naturietic factor (ANF); a marker of cardiac hypertrophy; was also increased with a subsequent increase in gross heart weights. Furthermore, there were derangements in both the number and the size of the mitochondria within CXCR4 cKO hearts. Moreover, CXCR4 cKO mice were more sensitive to catocholamines, their response to β-AR agonist challenge via acute isoproterenol (ISO) infusion demonstrated a greater increase in ejection fraction, dp/dtmax, and contractility index. Interestingly, prior to ISO infusion, there were significant differences in baseline hemodynamics between the CXCR4 cKO compared to littermate controls. However, upon administering ISO, the CXCR4 cKO responded in a robust manner overcoming the baseline hemodynamic deficits reaching WT values supporting our previous data that CXCR4 negatively regulates β-AR signaling. This further supports that, in the absence of the physiologic negative modulation, there is an overactivation of down-stream pathways, which contribute to the development and progression of contractile dysfunction. Our results demonstrated that CXCR4 plays a non-developmental role in regulating cardiac function and that CXCR4 cKO mice develop a progressive cardiomyopathy leading to clinical heart failure.

scholarly journals Toll-Like Receptor 9 Promotes Cardiac Inflammation and Heart Failure during Polymicrobial Sepsis

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Ralph Lohner ◽  
Markus Schwederski ◽  
Carolin Narath ◽  
Johanna Klein ◽  
Georg D. Duerr ◽  
...  
Keyword(s):  
Heart Failure ◽  
Peritoneal Cavity ◽  
Heart Function ◽  
Bacterial Load ◽  
Systolic Pressure ◽  
Polymicrobial Sepsis ◽  
Toll Like Receptor ◽  
Cardiac Inflammation ◽  
Continuous Release

Background. Aim was to elucidate the role of toll-like receptor 9 (TLR9) in cardiac inflammation and septic heart failure in a murine model of polymicrobial sepsis.Methods. Sepsis was induced via colon ascendens stent peritonitis (CASP) in C57BL/6 wild-type (WT) and TLR9-deficient (TLR9-D) mice. Bacterial load in the peritoneal cavity and cardiac expression of inflammatory mediators were determined at 6, 12, 18, 24, and 36 h. Eighteen hours after CASP cardiac function was monitoredin vivo. Sarcomere length of isolated cardiomyocytes was measured at 0.5 to 10 Hz after incubation with heat-inactivated bacteria.Results. CASP led to continuous release of bacteria into the peritoneal cavity, an increase of cytokines, and differential regulation of receptors of innate immunity in the heart. Eighteen hours after CASP WT mice developed septic heart failure characterised by reduction of end-systolic pressure, stroke volume, cardiac output, and parameters of contractility. This coincided with reduced cardiomyocyte sarcomere shortening. TLR9 deficiency resulted in significant reduction of cardiac inflammation and a sustained heart function. This was consistent with reduced mortality in TLR9-D compared to WT mice.Conclusions. In polymicrobial sepsis TLR9 signalling is pivotal to cardiac inflammation and septic heart failure.

Impact of exercise training on ventricular properties in a canine model of congestive heart failure

1997 ◽  
Vol 272 (3) ◽  
pp. H1382-H1390 ◽  
Author(s):  
K. Todaka ◽  
J. Wang ◽  
G. H. Yi ◽  
M. Knecht ◽  
R. Stennett ◽  
...  
Keyword(s):  
Heart Failure ◽  
Exercise Training ◽  
Heart Function ◽  
Systolic Pressure ◽  
Cardiac Pacing ◽  
Left Ventricular ◽  
Lv Function ◽  
Myocardial Stiffness

Exercise training improves functional class in patients with chronic heart failure (CHF) via effects on the periphery with no previously documented effect on intrinsic left ventricular (LV) properties. However, because methods used to evaluate in vivo LV function are limited, it is possible that some effects of exercise training on the failing heart have thus far eluded detection. Twelve dogs were instrumented for cardiac pacing and hemodynamic recordings. Hearts were paced rapidly for 4 wk. Six of the dogs received daily treadmill exercise (CHF(EX), 4.4 km/h, 2 h/day) concurrent with rapid pacing, while the other dogs remained sedentary (CHFs). Hemodynamic measurements taken in vivo at the end of 4 wk revealed relative preservation of maximum rate of pressure rise (2,540 +/- 440 vs. 1,720 +/- 300 mmHg/s, P < 0.05) and LV end-diastolic pressure (9 +/- 5 vs. 19 +/- 4 mmHg, P < 0.05) in CHF(EX) compared with CHFs. The hearts were then isolated and cross perfused for in vitro measurement of isovolumic pressure-volume relations; these results were compared with those of six normal dogs (N). Systolic function was similarly depressed in both groups of pacing animals [end-systolic elastance (Ees) values of 1.66 +/- 0.47 in CHFs, 1.77 +/- 0.38 in CHF(EX), and 3.05 +/- 0.81 mmHg/ml in N, with no changes in volume axis interceptors of the end-systolic pressure-volume relationship]. The diastolic myocardial stiffness constant, k, was elevated in CHFs and was normalized by exercise training (32 +/- 3 in CHFs, 21 +/- 3 in CHF(EX), 20 +/- 4 in N). Thus daily exercise training preserved in vivo hemodynamics during 4 wk of rapid cardiac pacing and was accompanied by a significant change in diastolic myocardial stiffness in vitro. These findings suggest that changes in heart function may contribute to the overall beneficial hemodynamic effects of exercise training in CHF by a significant effect on diastolic properties.

Abstract 202: Early Reprogramming Derived Cocktail FIJs Supports Cardiomyocyte Proliferation for Heart Regeneration

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Yuan-Yuan Cheng
Keyword(s):  
Morphological Changes ◽  
Heart Function ◽  
Sterol Synthesis ◽  
Heart Regeneration ◽  
Ki 67 ◽  
Adult Mice ◽  
Sequence Of Events ◽  
Proliferative Ability

Although remnant cardiomyocytes (CMs) possess a certain degree of proliferative ability, their regenerative efficiency is too low for cardiac regeneration after injury. As terminally differentiated cells, CMs are considered difficult to successfully reprogram into iPSCs. In this study, a modified reprogramming method was employed to avoid damage to the CMs, and the resulting CM-derived iPSCs were characterized their pluripotency and differentiative abilities. During the early stages of reprogramming, we observed sequential morphological changes in both CMs and non-CMs, but alkaline phosphatase assay revealed that CMs demonstrate a time-delayed sequence of events compared to non-CMs. In order to identify the specific events preceding colony formation, total RNA was purified for microarray analysis on day 0, 2, 4, and 6 of the reprogramming process. There were several interesting changes revealing such as up-regulation of sterol synthesis in non-CMs and down-regulation of chemokines in CMs on day 2. Most importantly, we detected significant enhanced mitosis for CMs on day 2. Nevertheless, typical iPSC-like colonies were clearly observed after 6 days of reprogramming in both cell types. In the purpose of bringing CM back to regain proliferative ability for heart regeneration, the candidates were selected from the microarray results on day 2 of the reprogramming. Triple combined gene cocktail FIJs was determined supporting CM proliferation with 7 times higher Ki-67 + or H3P + population % in neonatal murine CMs in vitro . The same supportive role of FIJs was also confirmed in adult mice showing higher H3P + adult CMs in vivo . Furthermore, heart function detected by echocardiography was significantly improved and less fibrosis shown by trichrome staining after the triple gene cocktail treatment in adult mice suffering from myocardial infarction, and this improvement was owing to the enhanced CM proliferation. In conclusion, triple gene cocktail selected from CM reprogramming day 2 provides valuable information for inducing remnant CM proliferation for heart regeneration.

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