Mitochondrial calcium increase induced by RyR1 and IP3R channel activation after membrane depolarization regulates skeletal muscle metabolism
Author
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Díaz Vegas, Alexis
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Córdova, A.
Author
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Valladares, Denisse
Author
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Llanos Vidal, Paola
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Hidalgo, C.
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Gherardi, Gaia
Author
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Stefani, Diego De
Author
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Mammucari, Cristina
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Rizzuto, Rosario
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Contreras Ferrat, Ariel Eduardo
Author
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Jaimovich Pérez, Enrique
Admission date
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2018-11-08T20:30:43Z
Available date
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2018-11-08T20:30:43Z
Publication date
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2018-06
Cita de ítem
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Frontiers in Physiology Volumen: 9 Número de artículo: 791
es_ES
Identifier
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10.3389/fphys.2018.00791
Identifier
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https://repositorio.uchile.cl/handle/2250/152524
Abstract
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Aim: We hypothesize that both type-1 ryanodine receptor (RyR1) and IP3-receptor (IP3R) calcium channels are necessary for the mitochondrial Ca2+ increase caused by membrane depolarization induced by potassium (or by electrical stimulation) of single skeletal muscle fibers; this calcium increase would couple muscle fiber excitation to an increase in metabolic output from mitochondria (excitation-metabolism coupling).
Methods: Mitochondria matrix and cytoplasmic Ca2+ levels were evaluated in fibers isolated from flexor digitorium brevis muscle using plasmids for the expression of a mitochondrial Ca2+ sensor (CEPIA3mt) or a cytoplasmic Ca2+ sensor (RCaMP). The role of intracellular Ca2+ channels was evaluated using both specific pharmacological inhibitors (xestospongin B for IP3R and Dantrolene for RyR1) and a genetic approach (shIP(3)R1-RFP). O-2 consumption was detected using Seahorse Extracellular Flux Analyzer.
Results: In isolated muscle fibers cell membrane depolarization increased both cytoplasmic and mitochondrial Ca2+ levels. Mitochondrial C-a2+ uptake required functional inositol IP3R and RyR1 channels. Inhibition of either channel decreased basal O-2 consumption rate but only RyR1 inhibition decreased ATP-linked O-2 consumption. Cell membrane depolarization-induced Ca2+ signals in sub-sarcolemmal mitochondria were accompanied by a reduction in mitochondrial membrane potential; Ca2+ signals propagated toward intermyofibrillar mitochondria, which displayed increased membrane potential. These results are compatible with slow, Ca2+-dependent propagation of mitochondrial membrane potential from the surface toward the center of the fiber.
Conclusion: Ca2+-dependent changes in mitochondrial membrane potential have different kinetics in the surface vs. the center of the fiber; these differences are likely to play a critical role in the control of mitochondrial metabolism, both at rest and after membrane depolarization as part of an excitation-metabolism coupling process in skeletal muscle fibers.
es_ES
Patrocinador
dc.description.sponsorship
FONDECYT
1151293
AT 21150604
11150243
BNI-09-15-F
11130267