Mari Kalda is defending her thesis on Mechanoenergetics of a Single Cardiomyocyte. Defense is on 10 December 2015 at 10:00 in the Institute of Cybernetics, room B101.
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Cross-Bridge Group Ensembles Describing Cooperativity in Thermodynamically Consistent Way

Kalda M, Peterson P, Vendelin M
PLoS ONE 2015;10(9):e0137438
PMID: 26361396
Full text: http://doi.org/10.1371/journal.pone.0137438
Abstract
The aim of this work is to incorporate cooperativity into Huxley-type cross-bridge model in thermodynamically consistent way. While the Huxley-type models assume that cross-bridges act independently from each other, we take into account that each cross-bridge is influenced by its neighbors and cooperativity is induced by tropomyosin movement. For that...
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Thesis defense: Niina Karro

Niina Karro is defending her thesis on Analysis of ADP Compartmentation in Cardiomyocytes and Its Role in Protection Against Mitochondrial Permeability Transition Pore Opening. Defense is on 5 October 2015 at 14:00 in the Institute of Cybernetics, room B101.
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The location of energetic compartments affects energetic communication in cardiomyocytes

Birkedal R, Laasmaa M, Vendelin M
Front Physiol 2014;5:376
PMID: 25324784
Full text: http://dx.doi.org/10.3389/fphys.2014.00376
Abstract
The heart relies on accurate regulation of mitochondrial energy supply to match energy demand. The main regulators are Ca(2+) and feedback of ADP and Pi. Regulation via feedback has intrigued for decades. First, the heart exhibits a remarkable metabolic stability. Second, diffusion of ADP and other molecules is restricted specifically in heart an...
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Tight coupling of Na+/K+-ATPase with glycolysis demonstrated in permeabilized rat cardiomyocytes

Sepp M, Sokolova N, Jugai S, Mandel M, Peterson P, Vendelin M
PLoS ONE 2014;9(6):e99413
PMID: 24932585
Abstract
The effective integrated organization of processes in cardiac cells is achieved, in part, by the functional compartmentation of energy transfer processes. Earlier, using permeabilized cardiomyocytes, we demonstrated the existence of tight coupling between some of cardiomyocyte ATPases and glycolysis in rat. In this work, we studied contribution of two membrane ATPases and w...
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ADP protects cardiac mitochondria under severe oxidative stress

Sokolova N, Pan S, Provazza S, Beutner G, Vendelin M, Birkedal R, Sheu SS
PLoS ONE 2013;8(12):e83214
PMID: 24349464
Abstract
ADP is not only a key substrate for ATP generation, but also a potent inhibitor of mitochondrial permeability transition pore (mPTP). In this study, we assessed how oxidative stress affects the potency of ADP as an mPTP inhibitor and whether its reduction of reactive oxygen species (ROS) production might be involved. We determined quantitatively the effects of ...
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Unchanged mitochondrial organization and compartmentation of high-energy phosphates in creatine-deficient GAMT-/- mouse hearts

Branovets J, Sepp M, Kotlyarova S, Jepihhina N, Sokolova N, Aksentijevic D, Lygate CA, Neubauer S, Vendelin M, Birkedal R
Am. J. Physiol. Heart Circ. Physiol. 2013 Aug;305(4):H506-20
PMID: 23792673
Abstract
Disruption of the creatine kinase (CK) system in hearts of CK-deficient mice leads to changes in the ultrastructure and regulation of mitochondrial respiration. We expected to see similar changes in creatine-deficient mice, which lack the enzyme guanidinoacetate methyltr...
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Real-time determination of sarcomere length of a single cardiomyocyte during contraction

Peterson P, Kalda M, Vendelin M
Am. J. Physiol., Cell Physiol. 2013 Mar;304(6):C519-31
PMID: 23255581
Abstract
Sarcomere length of a cardiomyocyte is an important control parameter for physiology studies on a single cell level; for instance, its accurate determination in real time is essential for performing single cardiomyocyte contraction experiments. The aim of this work is to develop an efficient and accurate method for estimating a mean sarcomere length of a contracting cardiomy...
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Sensitivity analysis of flux determination in heart by H₂ ¹⁸O -provided labeling using a dynamic Isotopologue model of energy transfer pathways

Schryer DW, Peterson P, Illaste A, Vendelin M
PLoS Comput. Biol. 2012;8(12):e1002795
PMID: 23236266
Abstract
To characterize intracellular energy transfer in the heart, two organ-level methods have frequently been employed: ³¹P − NMR inversion and saturation transfer, and dynamic ¹⁸O labeling. Creatine kinase (CK) fluxes obtained by following oxygen labeling have been considerably smaller than the fluxes determined by ³¹P − NMR saturation transfer. It has been proposed that dynamic ¹...
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Analysis of molecular movement reveals latticelike obstructions to diffusion in heart muscle cells

Illaste A, Laasmaa M, Peterson P, Vendelin M
Biophys. J. 2012 Feb;102(4):739-48
PMID: 22385844
Abstract
Intracellular diffusion in muscle cells is known to be restricted. Although characteristics and localization of these restrictions is yet to be elucidated, it has been established that ischemia-reperfusion injury reduces the overall diffusion restriction. Here we apply an extended version of raster image correlation spectroscopy to determine directional anisotropy and coefficients ...
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