Abstract 5400: Increase In Actin O -GlcNAcylation After Acute Exposure to N-Acetyl-D Glucosamine Influences Myofilament Calcium Sensitivity

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Genaro A Ramirez Correa ◽  
Wenhai Jin ◽  
Zihao Wang ◽  
Zhong Xin ◽  
Wei D Gao ◽  
...  
Keyword(s):  
Troponin I ◽  
Contractile Function ◽  
Physiological Role ◽  
Calcium Sensitivity ◽  
Acute Exposure ◽  
Hill Coefficient ◽  
Post Translational Modification ◽  
Opposite Pattern ◽  
Site Mapping ◽  
Cardiac Myofilament

Recently, we have identified specific sites of O -GlcNAcylation in major cardiac myofilament proteins. We used a methodology based on GalNaz-Biotin labeling followed by DTT switch and LC-MS/MS site mapping. As a result, 42 O- GlcNAc peptides from cardiac myofilaments were identified, corresponding to 32 of cardiac myosin heavy chain (MHC), 6 of α-sarcomeric actin, 2 of myosin light chain 1 (MLC1), 1 of MLC2, and 1 of troponin I (cTnI). Most of the identified O -GlcNAcylation sites are novel post-translational modification sites. To assess the potential physiological role of myofilament GlcNAcylation, Force-Calcium relationships studies were performed on skinned rat trabeculae. We have previously reported that exposure to GlcNAc but not Glycerol significantly decreases calcium sensitivity, further investigation confirm these preliminary findings (pCa 50 1.81 ± 0.13 μM for Control vs. 3.83 ± 0.44 μM for GlcNAc, n =7, P <=.001), and in addition demonstrate that maximal force (F max ) and Hill coefficient ( n ) are not significantly changed. Troponin I phosphorylation at Ser23, 24 was determined in three pooled trabeculea by WB using a specific antibody phosphor-TnI (Cell Signaling) normalized to actin signal (GlcNAc 0.722 vs Glycerol 0.667 A.U., n=3, p=NS). Phosphorylation at this PKA sites was ruled out as responsible for myofilament desensitization. Acute exposure of cardiac myofilaments to GlcNAc significantly increased α-sarcomeric actin O -GlcNAcylation from 27.6±4.2% to 35.1±2.36% ( n = 4, p<0.05) whereas total GlcNAcylation levels were unchanged. Additionally, we showed by immunofluoresence that O-GlcNAc transferase (OGT) and O-GlcNAcase (OGase) are abundant in rat hearts, OGT localizes predominantly in cardiac nuclei and less in cytoplasm, whereas OGase shows the opposite pattern. These studies provides the first site mapping of O -GlcNAcylation sites in cardiac myofilament proteins, and demonstrates their potential role in regulating myocardial contractile function. Regulation of myofilament O -GlcNAcylation may represent a novel and useful therapeutic target in heart failure, especially in diabetic cardiomyopathy.

scholarly journals Computational modeling of Takotsubo cardiomyopathy: effect of spatially varying β-adrenergic stimulation in the rat left ventricle

2014 ◽  
Vol 307 (10) ◽  
pp. H1487-H1496 ◽  
Author(s):  
Sander Land ◽  
Steven A. Niederer ◽  
William E. Louch ◽  
Åsmund T. Røe ◽  
Jan Magnus Aronsen ◽  
...  
Keyword(s):  
Left Ventricle ◽  
Takotsubo Cardiomyopathy ◽  
Troponin I ◽  
Contractile Function ◽  
Single Cells ◽  
Apical Ballooning ◽  
Calcium Sensitivity ◽  
Takotsubo Syndrome ◽  
Adrenergic Stimulation ◽  
Inotropic Effects

In Takotsubo cardiomyopathy, the left ventricle shows apical ballooning combined with basal hypercontractility. Both clinical observations in humans and recent experimental work on isolated rat ventricular myocytes suggest the dominant mechanisms of this syndrome are related to acute catecholamine overload. However, relating observed differences in single cells to the capacity of such alterations to result in the extreme changes in ventricular shape seen in Takotsubo syndrome is difficult. By using a computational model of the rat left ventricle, we investigate which mechanisms can give rise to the typical shape of the ventricle observed in this syndrome. Three potential dominant mechanisms related to effects of β-adrenergic stimulation were considered: apical-basal variation of calcium transients due to differences in L-type and sarco(endo)plasmic reticulum Ca2+-ATPase activation, apical-basal variation of calcium sensitivity due to differences in troponin I phosphorylation, and apical-basal variation in maximal active tension due to, e.g., the negative inotropic effects of p38 MAPK. Furthermore, we investigated the interaction of these spatial variations in the presence of a failing Frank-Starling mechanism. We conclude that a large portion of the apex needs to be affected by severe changes in calcium regulation or contractile function to result in apical ballooning, and smooth linear variation from apex to base is unlikely to result in the typical ventricular shape observed in this syndrome. A failing Frank-Starling mechanism significantly increases apical ballooning at end systole and may be an important additional factor underpinning Takotsubo syndrome.

scholarly journals Increased myocyte calcium sensitivity in end-stage pediatric dilated cardiomyopathy

2019 ◽  
Vol 317 (6) ◽  
pp. H1221-H1230 ◽  
Author(s):  
Stephanie J. Nakano ◽  
John S. Walker ◽  
Lori A. Walker ◽  
Xiaotao Li ◽  
Yanmei Du ◽  
...  
Keyword(s):  
Dilated Cardiomyopathy ◽  
Protein Phosphorylation ◽  
Troponin I ◽  
Systolic Dysfunction ◽  
Calcium Sensitivity ◽  
Contractile Properties ◽  
Hill Coefficient ◽  
Compensatory Response ◽  
Sarcomeric Protein ◽  
End Stage

Dilated cardiomyopathy (DCM) is the most common cause of heart failure (HF) in children, resulting in high mortality and need for heart transplantation. The pathophysiology underlying pediatric DCM is largely unclear; however, there is emerging evidence that molecular adaptations and response to conventional HF medications differ between children and adults. To gain insight into alterations leading to systolic dysfunction in pediatric DCM, we measured cardiomyocyte contractile properties and sarcomeric protein phosphorylation in explanted pediatric DCM myocardium ( N = 8 subjects) compared with nonfailing (NF) pediatric hearts ( N = 8 subjects). Force-pCa curves were generated from skinned cardiomyocytes in the presence and absence of protein kinase A. Sarcomeric protein phosphorylation was quantified with Pro-Q Diamond staining after gel electrophoresis. Pediatric DCM cardiomyocytes demonstrate increased calcium sensitivity (pCa50 =5.70 ± 0.0291), with an associated decrease in troponin (Tn)I phosphorylation compared with NF pediatric cardiomyocytes (pCa50 =5.59 ± 0.0271, P = 0.0073). Myosin binding protein C and TnT phosphorylation are also lower in pediatric DCM, whereas desmin phosphorylation is increased. Pediatric DCM cardiomyocytes generate peak tension comparable to that of NF pediatric cardiomyocytes [DCM 29.7 mN/mm2, interquartile range (IQR) 21.5–49.2 vs. NF 32.8 mN/mm2, IQR 21.5–49.2 mN/mm2; P = 0.6125]. In addition, cooperativity is decreased in pediatric DCM compared with pediatric NF (Hill coefficient: DCM 1.56, IQR 1.31–1.94 vs. NF 1.94, IQR 1.36–2.86; P = 0.0425). Alterations in sarcomeric phosphorylation and cardiomyocyte contractile properties may represent an impaired compensatory response, contributing to the detrimental DCM phenotype in children. NEW & NOTEWORTHY Our study is the first to demonstrate that cardiomyocytes from infants and young children with dilated cardiomyopathy (DCM) exhibit increased calcium sensitivity (likely mediated by decreased troponin I phosphorylation) compared with nonfailing pediatric cardiomyocytes. Compared with published values in adult cardiomyocytes, pediatric cardiomyocytes have notably decreased cooperativity, with a further reduction in the setting of DCM. Distinct adaptations in cardiomyocyte contractile properties may contribute to a differential response to pharmacological therapies in the pediatric DCM population.

scholarly journals Selective TNF-α targeting with infliximab attenuates impaired oxygen metabolism and contractile function induced by an acute exposure to air particulate matter

2015 ◽  
Vol 309 (10) ◽  
pp. H1621-H1628 ◽  
Author(s):  
Timoteo Marchini ◽  
Verónica D'Annunzio ◽  
Mariela L. Paz ◽  
Lourdes Cáceres ◽  
Mariana Garcés ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Saline Solution ◽  
Contractile Function ◽  
Left Ventricular ◽  
Acute Exposure ◽  
Control Group ◽  
Contractile Reserve ◽  
Mice Model ◽  
Cardiovascular Morbidity And Mortality ◽  
Tnf Α

Inflammation plays a central role in the onset and progression of cardiovascular diseases associated with the exposure to air pollution particulate matter (PM). The aim of this work was to analyze the cardioprotective effect of selective TNF-α targeting with a blocking anti-TNF-α antibody (infliximab) in an in vivo mice model of acute exposure to residual oil fly ash (ROFA). Female Swiss mice received an intraperitoneal injection of infliximab (10 mg/kg body wt) or saline solution, and were intranasally instilled with a ROFA suspension (1 mg/kg body wt). Control animals were instilled with saline solution and handled in parallel. After 3 h, heart O2 consumption was assessed by high-resolution respirometry in left ventricle tissue cubes and isolated mitochondria, and ventricular contractile reserve and lusitropic reserve were evaluated according to the Langendorff technique. ROFA instillation induced a significant decrease in tissue O2 consumption and active mitochondrial respiration by 32 and 31%, respectively, compared with the control group. While ventricular contractile state and isovolumic relaxation were not altered in ROFA-exposed mice, impaired contractile reserve and lusitropic reserve were observed in this group. Infliximab pretreatment significantly attenuated the decrease in heart O2 consumption and prevented the decrease in ventricular contractile and lusitropic reserve in ROFA-exposed mice. Moreover, infliximab-pretreated ROFA-exposed mice showed conserved left ventricular developed pressure and cardiac O2 consumption in response to a β-adrenergic stimulus with isoproterenol. These results provides direct evidence linking systemic inflammation and altered cardiac function following an acute exposure to PM and contribute to the understanding of PM-associated cardiovascular morbidity and mortality.

Relation between contractile function and regulatory cardiac proteins in hypertrophied hearts

1996 ◽  
Vol 270 (6) ◽  
pp. H2021-H2028 ◽  
Author(s):  
B. Stein ◽  
S. Bartel ◽  
U. Kirchhefer ◽  
S. Kokott ◽  
E. G. Krause ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Troponin I ◽  
Contractile Function ◽  
Papillary Muscles ◽  
Camp Accumulation ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
C Protein ◽  
Camp Formation ◽  
Phosphate Incorporation

The aim of this study was to examine the mechanism(s) underlying the reduced isoproterenol-induced positive inotropic and lusitropic effects in hypertrophied hearts. Chronic beta-adrenergic stimulation (2.4 mg isoproterenol.kg-1. day-1 for 4 days) induced cardiac hypertrophy by 33 +/- 2% in rats. A parallel downregulation of phospholamban (PLB) and sarcoplasmic reticulum Ca2(+)-ATPase (SERCA2) protein expression by 49 and 40%, respectively, was observed, whereas troponin I (TNI) and C protein remained unchanged. In papillary muscles from chronically beta-adrenergically stimulated rats, the isoproterenol-induced positive inotropic and lusitropic effects, as well as adenosine 3',5'-cyclic monophosphate (cAMP) accumulation, were attenuated compared with those in control animals. Acute exposure to isoproterenol induced phosphate incorporation into PLB, TNI, and C protein of 48 +/- 4.6, 55 +/- 5.0, and 27 +/- 4.9 pmol/mg homogenate protein, respectively, in control animals. In the hypertrophied hearts, phosphate incorporation into PLB was reduced by 76%, whereas phosphate incorporation into TNI or C protein remained unchanged. In conclusion, chronic beta-adrenergic stimulation reduced the isoproterenol-stimulated positive inotropic and lusitropic effects in papillary muscles, which were accompanied by 1) diminished cAMP formation, 2) attenuation of cAMP-mediated PLB phosphorylation, and 3) downregulation of PLB and SERCA2 protein.

scholarly journals Serotonin increases L-type Ca2+ current and SR Ca2+ content through 5-HT4 receptors in failing rat ventricular cardiomyocytes

2007 ◽  
Vol 293 (4) ◽  
pp. H2367-H2376 ◽  
Author(s):  
Jon Arne Kro Birkeland ◽  
Fredrik Swift ◽  
Nils Tovsrud ◽  
Ulla Enger ◽  
Per Kristian Lunde ◽  
...  
Keyword(s):  
Myosin Light Chain ◽  
Troponin I ◽  
Contractile Function ◽  
Left Ventricular ◽  
Inotropic Response ◽  
Receptor Stimulation ◽  
Ventricular Cardiomyocytes ◽  
Myosin Light Chain 2 ◽  
Intracellular Ca ◽  
Male Wistar Rats

Rats with congestive heart failure (CHF) develop ventricular inotropic responsiveness to serotonin (5-HT), mediated through 5-HT2A and 5-HT4 receptors. Human ventricle is similarly responsive to 5-HT through 5-HT4 receptors. We studied isolated ventricular cardiomyocytes to clarify the effects of 5-HT on intracellular Ca2+ handling. Left-ventricular cardiomyocytes were isolated from male Wistar rats 6 wk after induction of postinfarction CHF. Contractile function and Ca2+ transients were measured in field-stimulated cardiomyocytes, and L-type Ca2+ current ( ICa,L) and sarcoplasmic reticulum (SR) Ca2+ content were measured in voltage-clamped cells. Protein phosphorylation was measured by Western blotting or phosphoprotein gel staining. 5-HT4- and 5-HT2A-receptor stimulation induced a positive inotropic response of 33 and 18% (both P < 0.05) and also increased the Ca2+ transient (44 and 6%, respectively; both P < 0.05). ICa,L and SR Ca2+ content increased only after 5-HT4-receptor stimulation (57 and 65%; both P < 0.05). Phospholamban serine16 (PLB-Ser16) and troponin I phosphorylation increased by 26 and 13% after 5-HT4-receptor stimulation ( P < 0.05). 5-HT2A-receptor stimulation increased the action potential duration and did not significantly change the phosphorylation of PLB-Ser16 or troponin I, but it increased myosin light chain 2 (MLC2) phosphorylation. In conclusion, the positive inotropic response to 5-HT4 stimulation results from increased ICa,L and increased phosphorylation of PLB-Ser16, which increases the SR Ca2+ content. 5-HT4 stimulation is thus, like β-adrenoceptor stimulation, possibly energetically unfavorable in CHF. 5-HT2A-receptor stimulation, previously studied in acute CHF, induces a positive inotropic response also in chronic CHF, probably mediated by MLC2 phosphorylation.

scholarly journals Assessment of Left Atrial Function after ST-Segment Elevation Acute Myocardial Infarction: An Application of Real Time Three-Dimensional Echocardiography

2021 ◽  
Author(s):  
yuxia Miao ◽  
min Xu ◽  
yuetao Wang ◽  
xiao Xie ◽  
fei Liu ◽  
...  
Keyword(s):  
Real Time ◽  
Acute Phase ◽  
Troponin I ◽  
Contractile Function ◽  
Ventricular Outflow Tract ◽  
Left Ventricular ◽  
Functional Change ◽  
Multiple Time ◽  
St Segment Elevation ◽  
Creatine Kinase Mb

Objective: The purpose of this study is to evaluate the changes of LA size and function by real-time 3D echocardiography (RT-3DE), and provide a better understanding about their effects on treatment and prognosis. Methods: Ten Bama miniature pigs were used for modeling STEMI. Images were obtained by RT-3DE at multiple time points. From the LA volume-time relation curve, the LA volume (LAV) and functions (storage, channel, and active emptying) at different phases were calculated. Blood samples were obtained for measurements of NT-proBNP, creatine kinase-MB(CK-MB) and cardiac Troponin-I(cTn-I). Results: (1) LAVmax, LAVmin and LAVpre-a were all increased with time. (2) The LA expansion index was the most sensitive index of LA functional change. It increased (p< .05 vs. baseline) at the 1st day after STEMI (acute phase), and was correlated with diastolic function E/E’ (p< .05), as shown by univariate correlation analysis. (3) On the 28th day after STEMI, the active emptying percentage of total emptying (AE) showed a continuously increasing trend (p< .05), and was correlated with VTILVOT (time-velocity integral of left ventricular outflow tract) (p< .05). Conclusions: During the acute phase after STEMI, LA volume changed in order to increase LV preload. After STIMI, the storage function of LA was the first to change, while active contractile function was significantly enhanced during subacute phase. With the accurate measurement of LA function with RT-3DE, our study will help improving the therapeutic target setting and pharmacologic interventions, which may enhance the clinical outcomes of STEMI patients.

scholarly journals Heart Disease, Clinical Proteomics and Mass Spectrometry

2004 ◽  
Vol 20 (3) ◽  
pp. 167-178 ◽  
Author(s):  
Brian A. Stanley ◽  
Rebekah L. Gundry ◽  
Robert J. Cotter ◽  
Jennifer E. Van Eyk
Keyword(s):  
Heart Disease ◽  
Troponin I ◽  
Biomarker Discovery ◽  
Clinical Proteomics ◽  
Acute Injury ◽  
Therapeutic Monitoring ◽  
Post Translational Modification ◽  
Cardiac Biomarker ◽  
Mortality And Morbidity ◽  
Surface Enhanced

Heart disease is the leading cause of mortality and morbidity in the world. As such, biomarkers are needed for the diagnosis, prognosis, therapeutic monitoring and risk stratification of acute injury (acute myocardial infarction (AMI)) and chronic disease (heart failure). The procedure for biomarker development involves the discovery, validation, and translation into clinical practice of a panel of candidate proteins to monitor risk of heart disease. Two types of biomarkers are possible; heart-specific and cardiovascular pulmonary system monitoring markers. Here we review the use of MS in the process of cardiac biomarker discovery and validation by proteomic analysis of cardiac myocytes/tissue or serum/plasma. An example of the use of MS in biomarker discovery is given in which the albumin binding protein sub-proteome was examined using MALDI-TOF MS/MS. Additionally, an example of MS in protein validation is given using affinity surface enhanced laser desorption ionization (SELDI) to monitor the disease-induced post-translational modification and the ternary status of myoctye-originating protein, cardiac troponin I in serum.

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