Seppet 2001 Biochim Biophys Acta
| Seppet EK, Kaambre T, Sikk P, Tiivel T, Vija H, Tonkonogi M, Sahlin K, Kay L, Appaix F, Braun U, Eimre M, Saks VA (2001) Functional complexes of mitochondria with Ca,Mg ATPases of myofibrils and sarcoplasmic reticulum in muscle cells. Biochim Biophys Acta 1504:379-95. |
Seppet EK, Kaambre T, Sikk P, Tiivel T, Vija H, Tonkonogi M, Sahlin K, Kay L, Appaix F, Braun U, Eimre M, Saks VA (2001) Biochim Biophys Acta
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 300β400 ΞΌM. However, when ADP production was initiated by intracellular ATPase reactions, the ADP concentration in the medium leveled off at about 40 ΞΌM when about 70% of maximal rate of respiration was achieved. Respiration rate maintained by intracellular ATPases was suppressed about 20β30% 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 β with the MgATPases in myofibrils and Ca,MgATPases of sarcoplasmic reticulum. β’ Keywords: Muscle, Respiration, Mitochondrion, ADP, ATPase
β’ O2k-Network Lab: EE Tartu Paju K, FR Grenoble Saks VA, EE Tallinn Kaambre T
Labels:
Organism: Human
Tissue;cell: Skeletal muscle
Preparation: Permeabilized cells, Permeabilized tissue
HRR: Oxygraph-2k
