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1.

001-es BibID:BIBFORM015074
Első szerző:Borbély Attila (kardiológus)
Cím:Cardiomyocyte Stiffness in Diastolic Heart Failure / Borbély A., van der Velden J., Papp Z., Bronzwaer J. G. F., Edes I., Stienen G. J. M., Paulus W. J.
Dátum:2005
ISSN:0009-7322
Megjegyzések:Heart failure with preserved left ventricular (LV) ejection fraction (EF) is increasingly recognized and usually referred to as diastolic heart failure (DHF). Its pathogenetic mechanism remains unclear, partly because of a lack of myocardial biopsy material. Endomyocardial biopsy samples obtained from DHF patients were therefore analyzed for collagen volume fraction (CVF) and sarcomeric protein composition and compared with control samples. Single cardiomyocytes were isolated from these biopsy samples to assess cellular contractile performance.METHODS AND RESULTS: DHF patients (n=12) had an LVEF of 71+/-11%, an LV end-diastolic pressure (LVEDP) of 28+/-4 mm Hg, and no significant coronary artery stenoses. DHF patients had higher CVFs (7.5+/-4.0%, P<0.05) than did controls (n=8, 3.8+/-2.0%), and no conspicuous changes in sarcomeric protein composition were detected. Cardiomyocytes, mechanically isolated and treated with Triton X-100 to remove all membranes, were stretched to a sarcomere length of 2.2 microm and activated with solutions containing varying [Ca2+]. Compared with cardiomyocytes of controls, cardiomyocytes of DHF patients developed a similar total isometric force at maximal [Ca2+], but their resting tension (F(passive)) in the absence of Ca2+ was almost twice as high (6.6+/-3.0 versus 3.5+/-1.7 kN/m2, P<0.001). F(passive) and CVF combined yielded stronger correlations with LVEDP than did either alone. Administration of protein kinase A (PKA) to DHF cardiomyocytes lowered F(passive) to control values.CONCLUSIONS: DHF patients had stiffer cardiomyocytes, as evident from a higher F(passive) at the same sarcomere length. Together with CVF, F(passive) determined in vivo diastolic LV dysfunction. Correction of this high F(passive) by PKA suggests that reduced phosphorylation of sarcomeric proteins is involved in DHF.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Circulation. - 111 : 6 (2005), p. 774-781. -
További szerzők:Velden, Jolanda, van der Papp Zoltán (1965-) (kardiológus, élettanász) Bronzwaer, Jean G. F. Édes István (1952-) (kardiológus) Stienen, Ger J. M. Paulus, Walter J.
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2.

001-es BibID:BIBFORM010415
Első szerző:Borbély Attila (kardiológus)
Cím:Hypophosphorylation of the Stiff N2B titin isoform raises cardiomyocyte resting tension in failing human myocardium / Borbely, A., Falcao-Pires, I., van Heerebeek, L., Hamdani, N., Edes, I., Gavina, C., Leite-Moreira, A. F., Bronzwaer, J. G. F., Papp, Z., van der Velden, J., Stienen, G. J. M., Paulus, W. J.
Dátum:2009
ISSN:1524-4571 (Electronic)
Megjegyzések:High diastolic stiffness of failing myocardium results from interstitial fibrosis and elevated resting tension (F(passive)) of cardiomyocytes. A shift in titin isoform expression from N2BA to N2B isoform, lower overall phosphorylation of titin, and a shift in titin phosphorylation from N2B to N2BA isoform can raise F(passive) of cardiomyocytes. In left ventricular biopsies of heart failure (HF) patients, aortic stenosis (AS) patients, and controls (CON), we therefore related F(passive) of isolated cardiomyocytes to expression of titin isoforms and to phosphorylation of titin and titin isoforms. Biopsies were procured by transvascular technique (44 HF, 3 CON), perioperatively (25 AS, 4 CON), or from explanted hearts (4 HF, 8 CON). None had coronary artery disease. Isolated, permeabilized cardiomyocytes were stretched to 2.2-microm sarcomere length to measure F(passive). Expression and phosphorylation of titin isoforms were analyzed using gel electrophoresis with ProQ Diamond and SYPRO Ruby stains and reported as ratio of titin (N2BA/N2B) or of phosphorylated titin (P-N2BA/P-N2B) isoforms. F(passive) was higher in HF (6.1+/-0.4 kN/m(2)) than in CON (2.3+/-0.3 kN/m(2); P<0.01) or in AS (2.2+/-0.2 kN/m(2); P<0.001). Titin isoform expression differed between HF (N2BA/N2B=0.73+/-0.06) and CON (N2BA/N2B=0.39+/-0.05; P<0.001) and was comparable in HF and AS (N2BA/N2B=0.59+/-0.06). Overall titin phosphorylation was also comparable in HF and AS, but relative phosphorylation of the stiff N2B titin isoform was significantly lower in HF (P-N2BA/P-N2B=0.77+/-0.05) than in AS (P-N2BA/P-N2B=0.54+/-0.05; P<0.01). Relative hypophosphorylation of the stiff N2B titin isoform is a novel mechanism responsible for raised F(passive) of human HF cardiomyocytes.
Tárgyszavak:Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Aged
Biopsy
Elasticity
Female
Heart Failure
Humans
Male
Middle Aged
Muscle Proteins
Myocardium
Myocytes, Cardiac
Phosphorylation
Protein Isoforms
Protein Kinases
Sarcomeres
Megjelenés:Circulation Research. - 104 : 6 (2009), p. 780-786. -
További szerzők:Falcao-Pires, Ines Heerebeek, Loek, van Hamdani, Nazha Édes István (1952-) (kardiológus) Gavina, Cristina Leite-Moreira, Adelino F. Bronzwaer, Jean G. F. Papp Zoltán (1965-) (kardiológus, élettanász) Velden, Jolanda, van der Stienen, Ger J. M. Paulus, Walter J.
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3.

001-es BibID:BIBFORM003575
Első szerző:Borbély Attila (kardiológus)
Cím:Peroxynitrite-induced alpha-actinin nitration and contractile alterations in isolated human myocardial cells / Borbély A., Tóth A., Édes I., Virág L., Papp J. G., Varró A., Paulus W. J., van der Velden J., Stienen G. J. M., Papp Z.
Dátum:2005
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
myocytes
contractile function
peroxynitrite
alpha-actinin
human myocardium
Megjelenés:Cardiovascular Research. - 67 : 2 (2005), p. 225-233. -
További szerzők:Tóth Attila (1971-) (biológus) Édes István (1952-) (kardiológus) Virág László (1965-) (biokémikus, sejtbiológus, farmakológus) Papp Gy. Julius (Szeged) Varró András (1954-) (farmakológus, klinikai farmakológus) Paulus, Walter J. Velden, Jolanda, van der Stienen, Ger J. M. Papp Zoltán (1965-) (kardiológus, élettanász)
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4.

001-es BibID:BIBFORM030685
Első szerző:Czuriga Dániel (kardiológus)
Cím:Cardiomyocytes and cardiac contractile function / Dániel Czuriga, Ger J. M. Stienen, Jolanda van der Velden, Zoltán Papp
Dátum:2009
Megjegyzések:Force measurements in isolated permeabilized cardiomyocytes allow the functional characterization of the Ca2+-regulated contractile myofilaments of the heart. Parallel biochemical assays support the interpretation of the mechanical data and the recognition of structure to function relations within the contractile protein machinery. These investigations assist understanding of the cardiac pump function at the molecular level under health (e.g. Frank-Starling mechanism, ?-adrenergic responses) and disease (e.g. chronic heart failure). Careful analyses of cardiac tissues obtained from failing human hearts and animal models of heart failure suggested the enhancement of Ca2+-sensitivity of isometric force production and alterations in the Ca2+-independent, passive force of cardiomyocytes during chronic heart failure, while in some models the Ca2+-dependent maximal force producing capacity of the cardiomyocytes was decreased. Of note, myofilament Ca2+-sensitivity and the increased passive force could be largely corrected by exposing the cardiomyocytes in vitro to the intracellular signaling molecule of the ?-adrenergic pathway, protein kinase A, indicative for hypophosphorylation of target proteins during heart failure. The impact of altered myofilament function in vivo depends on the interplay between cytosolic Ca2+ concentration and the myofilaments. Although limiting relaxation, an enhanced myofilament Ca2+-sensitivity would increase cardiomyocyte force production thereby promoting cardiac contractility. However, as systolic Ca2+ levels are supposedly reduced in failing cardiomyocytes, it may be speculated that myofilament dysfunction deteriorates cardiac performance in the remodelled myocardium. This is because an enhancement in myofilament Ca2+-sensitivity and passive force would both limit cardiac relaxation.
ISBN:978-81-7895-418-9
Tárgyszavak:Orvostudományok Elméleti orvostudományok könyvfejezet
Megjelenés:Advances in Cardiomyocyte Research / eds. Péter P. Nánási. - p. 227-244. -
További szerzők:Stienen, Ger J. M. Velden, Jolanda, van der Papp Zoltán (1965-) (kardiológus, élettanász)
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5.

001-es BibID:BIBFORM002144
Első szerző:Édes István Ferenc (kardiológus)
Cím:Rate of tension redevelopment is not modulated by sarcomere length in permeabilized human, murine, and porcine cardiomyocytes / Edes I. F., Czuriga D., Csányi G., Chlopicki S., Recchia F. A., Borbély A., Galajda Z., Edes I., van der Velden J., Stienen G. J., Papp Z.
Dátum:2007
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. - 293 : 1 (2007), p. R20-R29. -
További szerzők:Czuriga Dániel (1982-) (kardiológus) Csányi Gábor Chlopicki, Stefan Recchia, Fabio A. Borbély Attila (1978-) (kardiológus) Galajda Zoltán (1962-) (szívsebész, érsebész) Édes István (1952-) (kardiológus) Velden, Jolanda, van der Stienen, Ger J. M. Papp Zoltán (1965-) (kardiológus, élettanász)
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6.

001-es BibID:BIBFORM005631
Első szerző:Hamdani, Nazha
Cím:Myofilament dysfunction in cardiac disease from mice to men / Hamdani, N., de Waard, M., Messer, A. E., Boontje, N. M., Kooij, V., van Dijk, S., Versteilen, A., Lamberts, R., Merkus, D., Dos Remedios, C., Duncker, D. J., Borbely, A., Papp, Z., Paulus, W., Stienen, G. J. M., Marston, S. B., van der Velden, J.
Dátum:2008
ISSN:0142-4319 (Print)
Megjegyzések:In healthy human myocardium a tight balance exists between receptor-mediated kinases and phosphatases coordinating phosphorylation of regulatory proteins involved in cardiomyocyte contractility. During heart failure, when neurohumoral stimulation increases to compensate for reduced cardiac pump function, this balance is perturbed. The imbalance between kinases and phosphatases upon chronic neurohumoral stimulation is detrimental and initiates cardiac remodelling, and phosphorylation changes of regulatory proteins, which impair cardiomyocyte function. The main signalling pathway involved in enhanced cardiomyocyte contractility during increased cardiac load is the beta-adrenergic signalling route, which becomes desensitized upon chronic stimulation. At the myofilament level, activation of protein kinase A (PKA), the down-stream kinase of the beta-adrenergic receptors (beta-AR), phosphorylates troponin I, myosin binding protein C and titin, which all exert differential effects on myofilament function. As a consequence of beta-AR down-regulation and desensitization, phosphorylation of the PKA-target proteins within the cardiomyocyte may be decreased and alter myofilament function. Here we discuss involvement of altered PKA-mediated myofilament protein phosphorylation in different animal and human studies, and discuss the roles of troponin I, myosin binding protein C and titin in regulating myofilament dysfunction in cardiac disease. Data from the different animal and human studies emphasize the importance of careful biopsy procurement, and the need to investigate localization of kinases and phosphatases within the cardiomyocyte, in particular their co-localization with cardiac myofilaments upon receptor stimulation.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal of Muscle Research and Cell Motility. - 29 : 6-8 (2008), p. 189-201. -
További szerzők:de Waard, Monique Messer, Andrew E. Boontje, Nicky M. Kooij, Viola Dijk, Sabine, van Versteilen, Amanda Lamberts, Regis Merkus, Daphne Dos Remedios, Cris Duncker, Dirk J. Borbély Attila (1978-) (kardiológus) Papp Zoltán (1965-) (kardiológus, élettanász) Paulus, Walter J. Stienen, Ger J. M. Marston, Steven B. Velden, Jolanda, van der
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7.

001-es BibID:BIBFORM005633
Első szerző:Hertelendi Zita (orvos)
Cím:Oxidation of myofilament protein sulfhydryl groups reduces the contractile force and its Ca2+ sensitivity in human cardiomyocytes / Hertelendi, Z., Toth, A., Borbely, A., Galajda, Z., van der Velden, J., Stienen, G. J., Edes, I., Papp, Z.
Dátum:2008
ISSN:1557-7716 (Electronic)
Megjegyzések:This study sought to characterize the relation between the oxidation of protein sulfhydryl (SH) groups and Ca2+-activated force production in the human myocardium. Triton-permeabilized left ventricular cardiomyocytes from donor hearts were exposed to an oxidative (2,2'-dithiodipyridine, DTDP) agent in vitro, and the changes in isometric force, its Ca2+ sensitivity, the cross-bridge-sensitive rate constant of force redevelopment at saturating [Ca2+] (k(tr,max)), and protein SH oxidation were monitored. DTDP (0.1-10 mM for 2 min) oxidized the myocardial proteins and diminished the Ca2+-activated force with different concentration dependences (EC(50,SH) = 0.17 +/- 0.02 mM and EC(50,force) = 2.46 +/- 0.22 mM; mean +/- SEM). The application of 2.5 mM DTDP decreased the maximal Ca2+-activated force (to 64%), its Ca2+ sensitivity (DeltapCa(50) = 0.22 +/- 0.02), and the steepness of the Ca2+-force relation (n(Hill), from 2.01 +/- 0.08 to 1.76 +/- 0.08). These changes were paralleled by reductions in the free SH content of the proteins (to 15%) and in k(tr,max) (to 75%). SH-specific labeling identified SH oxidation of myosin light chain 1 and actin at DTDP concentrations at which the changes in the contractile parameters occurred. Our data suggest that SH oxidation in selected myofilament proteins diminishes the Ca2+-activated force and its Ca2+ sensitivity through an impaired Ca2+ regulation of the actin-myosin cycle in the human heart.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
2,2'-Dipyridyl
Adult
Blotting, Western
Calcium
Cell Shape
Cells, Cultured
Disulfides
Female
Humans
Immunoprecipitation
Male
Microfilaments
Middle Aged
Myocardial Contraction
Myocytes, Cardiac
Oxidation-Reduction
Proteins/chemistry
Sulfhydryl Compounds
Megjelenés:Antioxidants and Redox Signaling. - 10 : 7 (2008), p. 1175-1184. -
További szerzők:Tóth Attila (1971-) (biológus) Borbély Attila (1978-) (kardiológus) Galajda Zoltán (1962-) (szívsebész, érsebész) Velden, Jolanda, van der Stienen, Ger J. M. Édes István (1952-) (kardiológus) Papp Zoltán (1965-) (kardiológus, élettanász)
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8.

001-es BibID:BIBFORM065597
Első szerző:Papp Zoltán (kardiológus, élettanász)
Cím:Altered myocardial force generation in end-stage human heart failure / Zoltán Papp, Jolanda van der Velden, Attila Borbély, István Édes, Ger J. M. Stienen
Dátum:2014
ISSN:2055-5822
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:ESC Heart Failure. - 1 : 2 (2014), p. 160-165. -
További szerzők:Velden, Jolanda, van der Borbély Attila (1978-) (kardiológus) Édes István (1952-) (kardiológus) Stienen, Ger J. M.
Pályázati támogatás:TÁMOP-4.2.2.A-11/1/KONV-2012-0045
TÁMOP
Kardiológia Kutatócsoport
Health-2010; MEDIA-261409
FP7
4.2.4.A/2-11-1-2012-0001
TÁMOP
K 109083
OTKA
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9.

001-es BibID:BIBFORM040577
Első szerző:Papp Zoltán (kardiológus, élettanász)
Cím:Calpain-I induced alterations in the cytoskeletal structure and impaired mechanical properties of single myocytes of rat heart / Zoltán Papp, Jolanda van der Velden, G. J. M. Stienen
Dátum:2000
ISSN:0008-6363
Megjegyzések:Objective: The involvement of Calpain-I mediated proteolysis has been implicated in myofibrillar dysfunction of reperfused myocardium following ischemia (stunning). This study addresses the question whether ultrastructural alterations might be responsible for the depressed contractility. Methods: Mechanical properties and protein composition of isolated myocytes after Calpain-I exposure (1.25 U/ml; 10 min; 15°C; pCa 5.0) and of ischemic rat hearts following reperfusion were characterized. Results: Maximal isometric force (44±5 kN/m2) at pCa 4.5 (pCa=-log[Ca2+]) decreased by 42.5% in Triton permeabilized myocytes (n=11) after Calpain-I treatment. Force (and consequent myofilament disarrangement) during Calpain-I treatment was prevented by 40 mM BDM. The contractile force of Calpain-I exposed myocytes was significantly higher at submaximal levels of activation (pCa 5.5, 5.4 and 5.3) before maximal force development (pCa 4.5) than after maximal force development. The pCa50 value (5.40±0.02) determined from these initial test contractures did not differ significantly from that of untreated controls (5.44±0.03). However, after full activation Ca2+-sensitivity of force production in Calpain-I treated myocytes was significantly reduced (pCa50 5.34±0.02). This change in pCa50 was positively correlated with the reduction in maximal isometric force and was accompanied by sarcomere disorder. These findings imply that at least part of the Calpain-I induced mechanical alterations are dependent on force history. Measurements of the rate of force redevelopment after unloaded shortening suggested that Calpain-I did not affect cross-bridge kinetics. SDS gel electrophoresis and Western immunoblotting of Calpain-I treated myocytes revealed desmin degradation. The desmin content of postischemic myocardium was also reduced. Conclusion: Our results indicate that ultrastructural alterations may play an important role in the Calpain-I mediated cardiac dysfunction.
Tárgyszavak:Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Cardiovascular Research. - 45 : 4 (2000), p. 981-993. -
További szerzők:Velden, Jolanda, van der Stienen, Ger J. M.
Pályázati támogatás:NWO-OTKA
Egyéb
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10.

001-es BibID:BIBFORM030905
Első szerző:Papp Zoltán (kardiológus, élettanász)
Cím:Effects of Ca2+-sensitizers in permeabilized cardiac myocytes from donor and end-stage failing human hearts / Papp Z., van Der Velden J., Borbély A., Édes I., Stienen G. J. M.
Dátum:2004
Megjegyzések:During heart failure, alterations occur in contractile protein expression and phosphorylation, which may influence the effects of Ca2+ -sensitizers. To quantify the magnitude of these effects, isometric force was studied in mechanically isolated Triton-skinned myocytes from end-stage failing and non-failing donor hearts under control conditions (pH 7.2; no added inorganic phosphate (Pi)) and under mimicked ischemic conditions (pH 6.5; 10 mM Pi). Two different Ca2+ -sensitizers were used: EMD 53998 (10 microM), which exerts its influence through the actin-myosin interaction, and OR-1896 (10 microM) (the active metabolite of levosimendan), which affects the Ca2+ -sensory function of the thin filaments. The maximal force (Po) measured at saturating Ca2+ concentration and the resting force (Prest) determined in the virtual absence of Ca2+ (pCa 9) did not differ between the failing and non-failing myocytes, but the Ca2+ concentration required to induce the half-maximal force under control conditions was significantly lower in the failing than in the non-failing myocytes (DeltapCa50=0.15). This difference in Ca2+ -sensitivity, however, was abolished during mimicked ischemia. EMD 53998 increased Po and Prest by approximately 15% of Po and greatly enhanced the Ca2+ -sensitivity (DeltapCa50 > 0.25) of force production. OR-1896 did not affect Po and Prest, and provoked a small, but significant Ca2+ -sensitization (DeltapCa50 approximately 0.1). All of these effects were comparable in the donor and failing myocytes, but, in contrast with OR-1896, EMD 53998 considerably diminished the difference in the Ca2+ -sensitivities between the failing and non-failing myocytes. The action of Ca2+ -sensitizers under mimicked ischemic conditions was impaired to a similar degree in the donor and the failing myocytes. Our results indicate that the Ca2+ -activation of the myofibrillar system is altered in end-stage human heart failure. This modulates the effects of Ca2+ -sensitizers both under control and under mimicked ischemic conditions.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal of Muscle Research and Cell Motility. - 25 : 3 (2004), p. 219-224. -
További szerzők:Velden, Jolanda, van der Borbély Attila (1978-) (kardiológus) Édes István (1952-) (kardiológus) Stienen, Ger J. M.
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11.

001-es BibID:BIBFORM040606
Első szerző:Velden, Jolanda, van der
Cím:Calcium sensitivity of force in human ventricular cardiomyocytes from donor and failing hearts / van der Velden J., Boontje N. M., Papp Z., Klein L. J., Visser F. C., de Jong J. W., Owen V. J., Burton P. B., Stienen G. J.
Dátum:2002
ISSN:0300-8428
Megjegyzések:In failing human myocardium changes occur, in particular, in isoform composition and phosphorylation level of the troponin T (TnT) and troponin I (TnI) subunits of the actin filament and the myosin light chains (MLC-1 and -2), but it is unclear to what extent they influence cardiac performance. This overview concentrates on the relation between contractile function, contractile protein composition and phosphorylation levels in small biopsies from control (donor) hearts, from biopsies obtained during open heart surgery (NYHA Class I-IV) and from end-stage failing (explanted, NYHA class IV) hearts. Furthermore, attention is paid to the effect of the catalytic subunit of protein kinase A on isometric force development in single Triton-skinned human cardiomyocytes isolated from donor and end-stage failing left ventricular myocardium at different resting sarcomere lengths. A reduction in sarcomere length from 2.2 to 1.8 microm caused reductions in maximum isometric force by approximately 35% both in donor and in failing cardiomyocytes. The midpoints of the calcium sensitivity curves (pCa50) of donor and end-stage failing hearts differed markedly at all sarcomere lengths (mean delta pCa50 = 0.22). Our findings indicate that 1) TnI phosphorylation contributes to the differences in calcium sensitivity between donor and end-stage failing hearts, 2) human ventricular myocardium is heterogeneous with respect of the phosphorylation of TnT, MLC-2 and the isoform distribution of MLC-1 and MLC-2, and 3) the Frank-Starling mechanism is preserved in end-stage failing myocardium.
Tárgyszavak:Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Basic Research In Cardiology. - 97 : Suppl.1 (2002), p. 118-126. -
További szerzők:Boontje, Nicky M. Papp Zoltán (1965-) (kardiológus, élettanász) Klein, L. J. Visser, F. C. de Jong, J. W. Owen, V. J. Burton, P. B. Stienen, Ger J. M.
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12.

001-es BibID:BIBFORM040584
Első szerző:Velden, Jolanda, van der
Cím:The effect of myosin light chain 2 dephosphorylation on Ca2+ -sensitivity of force is enhanced in failing human hearts / van der Velden J., Papp Z., Boontje N. M., Zaremba R., de Jong J. W., Janssen P. M., Hasenfuss G., Stienen G. J.
Dátum:2003
ISSN:0008-6363
Megjegyzések:OBJECTIVE: Phosphorylation of the myosin light chain 2 (MLC-2) isoform expressed as a percentage of total MLC-2 was decreased in failing (21.1+/-2.0%) compared to donor (31.9+/-4.8%) hearts. To assess the functional implications of this change, we compared the effects of MLC-2 dephosphorylation on force development in failing and non-failing (donor) human hearts. METHODS: Cooperative effects in isometric force and rate of force redevelopment (K(tr)) were studied in single Triton-skinned human cardiomyocytes at various [Ca(2+)] before and after protein phosphatase-1 (PP-1) incubation. RESULTS: Maximum force and K(tr) values did not differ between failing and donor hearts, but Ca(2+)-sensitivity of force (pCa(50)) was significantly higher in failing myocardium (Deltap Ca(50)=0.17). K(tr) decreased with decreasing [Ca(2+)], although this decrease was less in failing than in donor hearts. Incubation of the myocytes with PP-1 (0.5 U/ml; 60 min) decreased pCa(50) to a larger extent in failing (0.20 pCa units) than in donor cardiomyocytes (0.10 pCa units). A decrease in absolute K(tr) values was found after PP-1 in failing and donor myocytes, while the shape of the K(tr)-Ca(2+) relationships remained unaltered. CONCLUSIONS: Surprisingly, the contractile response to MLC-2 dephosphorylation is enhanced in failing hearts, despite the reduced level of basal MLC-2 phosphorylation. The enhanced response to MLC-2 dephosphorylation in failing myocytes might result from differences in basal phosphorylation of other thin and thick filament proteins between donor and failing hearts. Regulation of Ca(2+)-sensitivity via MLC-2 phosphorylation may be a potential compensatory mechanism to reverse the detrimental effects of increased Ca(2+)-sensitivity and impaired Ca(2+)-handling on diastolic function in human heart failure.
Tárgyszavak:Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Cardiovascular Research. - 57 : 2 (2003), p. 505-514. -
További szerzők:Papp Zoltán (1965-) (kardiológus, élettanász) Boontje, Nicky M. Zaremba, Ruud de Jong, J. W. Janssen, P. M. L. Hasenfuß, Gerd Stienen, Ger J. M.
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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