News
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Restricted ADP movement in cardiomyocytes: Cytosolic diffusion obstacles are complemented with a small number of open mitochondrial voltage-dependent anion channels
Simson P, Jepihhina N, Laasmaa M, Peterson P, Birkedal R, Vendelin M J. Mol. Cell. Cardiol. Volume 97, August 2016, Pages 197–203; PMID: 27261153 Full text: http://doi.org/10.1016/j.yjmcc.2016.04.012 Abstract Adequate intracellular energy transfer is crucial for proper cardiac function. In energy starved failing hearts, partial restoration of energy transfer can rescue mechanical performance. There are two…
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Metabolic compartmentation in rainbow trout cardiomyocytes: coupling of hexokinase but not creatine kinase to mitochondrial respiration
Karro N, Sepp M, Jugai S, Laasmaa M, Vendelin M, Birkedal R J. Comp. Physiol. B, Biochem. Syst. Environ. Physiol. 2016 Aug; PMID: 27522222 Full text: http://doi.org/10.1007/s00360-016-1025-x Abstract Rainbow trout (Oncorhynchus mykiss) cardiomyocytes have a simple morphology with fewer membrane structures such as sarcoplasmic reticulum and t-tubules penetrating the cytosol. Despite this, intracellular ADP diffusion…
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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…
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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.…
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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…
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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…
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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…
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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…
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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…
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Molecular dynamics simulations of creatine kinase and adenine nucleotide translocase in mitochondrial membrane patch
Karo J, Peterson P, Vendelin M J. Biol. Chem. 2012 Mar;287(10):7467-76 PMID: 22241474 Abstract Interaction between mitochondrial creatine kinase (MtCK) and adenine nucleotide translocase (ANT) can play an important role in determining energy transfer pathways in the cell. Although the functional coupling between MtCK and ANT has been demonstrated, the precise mechanism of the coupling…