Functional complexes of mitochondria with MgATPase of myofibrils and sarcoplasmic reticulum in muscle cells
Document identifier: oai:dalea.du.se:2322
Keyword: Muscle; Respiration; Mitochondrion; ADP; ATPasePublication year: 2001Relevant Sustainable Development Goals (SDGs):
The SDG label(s) above have been assigned by OSDG.aiAbstract: Regulation of mitochondrial respiration in situ in the muscle cells was studied by using fully permeabilized muscle fibers and cardiomyocytes. The results show that the kinetics of regulation of mitochondrial respiration in situ by exogenous ADP are very different from the kinetics of its regulation by endogenous ADP. In cardiac and m. soleus fibers apparent Km for exogenous ADP in regulation of respiration was equal to 300–400 µM. However, when ADP production was initiated by intracellular ATPase reactions, the ADP concentration in the medium leveled off at about 40 µM when about 70% of maximal rate of respiration was achieved. Respiration rate maintained by intracellular ATPases was suppressed about 20–30% during exogenous trapping of ADP with excess pyruvate kinase (PK, 20 IU/ml) and phosphoenolpyruvate (PEP, 5 mM). ADP flux via the external PK+PEP system was decreased by half by activation of mitochondrial oxidative phosphorylation. Creatine (20 mM) further activated the respiration in the presence of PK+PEP. It is concluded that in oxidative muscle cells mitochondria behave as if they were incorporated into functional complexes with adjacent ADP producing systems – with the MgATPases in myofibrils and Ca,MgATPases of sarcoplasmic reticulum.
Authors
E. K. Seppet
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T. Kaambre
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P. Sikk
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T. Tiivel
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H. Vija
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L. Kay
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F. Appaix
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Michail Tonkonogi
Högskolan Dalarna; Medicinsk vetenskap
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Kent Sahlin
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U. Braun
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M. Eimre
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V.A. Saks
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header:
identifier: oai:dalea.du.se:2322
datestamp: 2021-04-15T12:57:27Z
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identifier: http://urn.kb.se/resolve?urn=urn:nbn:se:du-2322
titleInfo:
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lang: eng
title: Functional complexes of mitochondria with MgATPase of myofibrils and sarcoplasmic reticulum in muscle cells
abstract: Regulation of mitochondrial respiration in situ in the muscle cells was studied by using fully permeabilized muscle fibers and cardiomyocytes. The results show that the kinetics of regulation of mitochondrial respiration in situ by exogenous ADP are very different from the kinetics of its regulation by endogenous ADP. In cardiac and m. soleus fibers apparent Km for exogenous ADP in regulation of respiration was equal to 300–400 µM. However when ADP production was initiated by intracellular ATPase reactions the ADP concentration in the medium leveled off at about 40 µM when about 70% of maximal rate of respiration was achieved. Respiration rate maintained by intracellular ATPases was suppressed about 20–30% during exogenous trapping of ADP with excess pyruvate kinase (PK 20 IU/ml) and phosphoenolpyruvate (PEP 5 mM). ADP flux via the external PK+PEP system was decreased by half by activation of mitochondrial oxidative phosphorylation. Creatine (20 mM) further activated the respiration in the presence of PK+PEP. It is concluded that in oxidative muscle cells mitochondria behave as if they were incorporated into functional complexes with adjacent ADP producing systems – with the MgATPases in myofibrils and CaMgATPases of sarcoplasmic reticulum.
subject:
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lang: eng
topic: Muscle; Respiration; Mitochondrion; ADP; ATPase
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publication/journal-article
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Published
12
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Seppet
E. K.
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Kaambre
T.
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Sikk
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Tiivel
T.
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Vija
H.
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Kay
L.
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Appaix
F.
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Tonkonogi
Michail
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Högskolan Dalarna
Medicinsk vetenskap
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Sahlin
Kent
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Braun
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Eimre
M.
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Saks
V.A.
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originInfo:
dateIssued: 2001
publisher: Elsevier
place:
placeTerm: Amsterdam
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titleInfo:
title: Biochimica et Biophysica Acta - Bioenergetics
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0005-2728
1879-2650
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type: volume
number: 1504
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type: issue
number: 2-3
extent:
start: 379
end: 395
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