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ADP Compartmentation Analysis Reveals Coupling between Pyruvate Kinase and ATPases in Heart Muscle

Cardiomyocytes have intracellular diffusion restrictions, which spatially compartmentalize ADP and ATP. However, the models that predict diffusion restrictions have used data sets generated in rat heart permeabilized fibers, where diffusion distances may be heterogeneous. This is avoided by using is...

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Autores principales: Sepp, Mervi, Vendelin, Marko, Vija, Heiki, Birkedal, Rikke
Formato: Texto
Lenguaje:English
Publicado: The Biophysical Society 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2884246/
https://www.ncbi.nlm.nih.gov/pubmed/20550890
http://dx.doi.org/10.1016/j.bpj.2010.03.025
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author Sepp, Mervi
Vendelin, Marko
Vija, Heiki
Birkedal, Rikke
author_facet Sepp, Mervi
Vendelin, Marko
Vija, Heiki
Birkedal, Rikke
author_sort Sepp, Mervi
collection PubMed
description Cardiomyocytes have intracellular diffusion restrictions, which spatially compartmentalize ADP and ATP. However, the models that predict diffusion restrictions have used data sets generated in rat heart permeabilized fibers, where diffusion distances may be heterogeneous. This is avoided by using isolated, permeabilized cardiomyocytes. The aim of this work was to analyze the intracellular diffusion of ATP and ADP in rat permeabilized cardiomyocytes. To do this, we measured respiration rate, ATPase rate, and ADP concentration in the surrounding solution. The data were analyzed using mathematical models that reflect different levels of cell compartmentalization. In agreement with previous studies, we found significant diffusion restriction by the mitochondrial outer membrane and confirmed a functional coupling between mitochondria and a fraction of ATPases in the cell. In addition, our experimental data show that considerable activity of endogenous pyruvate kinase (PK) remains in the cardiomyocytes after permeabilization. A fraction of ATPases were inactive without ATP feedback by this endogenous PK. When analyzing the data, we were able to reproduce the measurements only with the mathematical models that include a tight coupling between the fraction of endogenous PK and ATPases. To our knowledge, this is the first time such a strong coupling of PK to ATPases has been demonstrated in permeabilized cardiomyocytes.
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spelling pubmed-28842462010-07-09 ADP Compartmentation Analysis Reveals Coupling between Pyruvate Kinase and ATPases in Heart Muscle Sepp, Mervi Vendelin, Marko Vija, Heiki Birkedal, Rikke Biophys J Biological Systems and Multicellular Dynamics Cardiomyocytes have intracellular diffusion restrictions, which spatially compartmentalize ADP and ATP. However, the models that predict diffusion restrictions have used data sets generated in rat heart permeabilized fibers, where diffusion distances may be heterogeneous. This is avoided by using isolated, permeabilized cardiomyocytes. The aim of this work was to analyze the intracellular diffusion of ATP and ADP in rat permeabilized cardiomyocytes. To do this, we measured respiration rate, ATPase rate, and ADP concentration in the surrounding solution. The data were analyzed using mathematical models that reflect different levels of cell compartmentalization. In agreement with previous studies, we found significant diffusion restriction by the mitochondrial outer membrane and confirmed a functional coupling between mitochondria and a fraction of ATPases in the cell. In addition, our experimental data show that considerable activity of endogenous pyruvate kinase (PK) remains in the cardiomyocytes after permeabilization. A fraction of ATPases were inactive without ATP feedback by this endogenous PK. When analyzing the data, we were able to reproduce the measurements only with the mathematical models that include a tight coupling between the fraction of endogenous PK and ATPases. To our knowledge, this is the first time such a strong coupling of PK to ATPases has been demonstrated in permeabilized cardiomyocytes. The Biophysical Society 2010-06-16 /pmc/articles/PMC2884246/ /pubmed/20550890 http://dx.doi.org/10.1016/j.bpj.2010.03.025 Text en © 2010 by the Biophysical Society. https://creativecommons.org/licenses/by-nc-nd/3.0/This is an open access article under the CC BY NC ND license (https://creativecommons.org/licenses/by-nc-nd/3.0/).
spellingShingle Biological Systems and Multicellular Dynamics
Sepp, Mervi
Vendelin, Marko
Vija, Heiki
Birkedal, Rikke
ADP Compartmentation Analysis Reveals Coupling between Pyruvate Kinase and ATPases in Heart Muscle
title ADP Compartmentation Analysis Reveals Coupling between Pyruvate Kinase and ATPases in Heart Muscle
title_full ADP Compartmentation Analysis Reveals Coupling between Pyruvate Kinase and ATPases in Heart Muscle
title_fullStr ADP Compartmentation Analysis Reveals Coupling between Pyruvate Kinase and ATPases in Heart Muscle
title_full_unstemmed ADP Compartmentation Analysis Reveals Coupling between Pyruvate Kinase and ATPases in Heart Muscle
title_short ADP Compartmentation Analysis Reveals Coupling between Pyruvate Kinase and ATPases in Heart Muscle
title_sort adp compartmentation analysis reveals coupling between pyruvate kinase and atpases in heart muscle
topic Biological Systems and Multicellular Dynamics
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2884246/
https://www.ncbi.nlm.nih.gov/pubmed/20550890
http://dx.doi.org/10.1016/j.bpj.2010.03.025
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