Cardiac responses to β-adrenoceptor stimulation is partly dependent on mitochondrial calcium uniporter activity
Background and Purpose: Despite the importance of mitochondrial Ca2+ to metabolic regulation and cell physiology, little is known about the mechanisms that regulate Ca2+ entry into the mitochondria. Accordingly, we established a system to determine the role of the mitochondrial Ca2+ uniporter in an...
| Autores: | , , , , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2014 |
| País: | Argentina |
| Institución: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositorio: | CONICET Digital (CONICET) |
| Idioma: | inglés |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/12024 |
| Acceso en línea: | http://hdl.handle.net/11336/12024 |
| Access Level: | acceso abierto |
| Palabra clave: | Mitochondria Biochemical Pharmacology Catecholamines Ion Channles https://purl.org/becyt/ford/3.1 https://purl.org/becyt/ford/3 |
| Sumario: | Background and Purpose: Despite the importance of mitochondrial Ca2+ to metabolic regulation and cell physiology, little is known about the mechanisms that regulate Ca2+ entry into the mitochondria. Accordingly, we established a system to determine the role of the mitochondrial Ca2+ uniporter in an isolated heart model, at baseline and during increased workload following β-adrenoceptor stimulation. Experimental Approach: Cardiac contractility, oxygen consumption and intracellular Ca2+ transients were measured in ex vivo perfused murine hearts. Ru360 and spermine were used to modify mitochondrial Ca2+ uniporter activity. Changes in mitochondrial Ca2+ content and energetic phosphate metabolite levels were determined. Key Results: The addition of Ru360, a selective inhibitor of the mitochondrial Ca2+ uniporter, induced progressively and sustained negative inotropic effects that were dose-dependent with an EC50 of 7 μM. Treatment with spermine, a uniporter agonist, showed a positive inotropic effect that was blocked by Ru360. Inotropic stimulation with isoprenaline elevated oxygen consumption (2.7-fold), Ca2+-dependent activation of pyruvate dehydrogenase (5-fold) and mitochondrial Ca2+ content (2.5-fold). However, in Ru360-treated hearts, this parameter was attenuated. In addition, β-adrenoceptor stimulation in the presence of Ru360 did not affect intracellular Ca2+ handling, PKA or Ca2+/calmodulin-dependent PK signalling. Conclusions and Implications: Inhibition of the mitochondrial Ca2+ uniporter decreases β-adrenoceptor response, uncoupling between workload and production of energetic metabolites. Our results support the hypothesis that the coupling of workload and energy supply is partly dependent on mitochondrial Ca2+ uniporter activity. |
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