Local energetic regulation of sarcoplasmic and myosin ATPase is differently impaired in rats with heart failure.: Local energy regulation is impaired in HF rats

Autor: Joubert, Frederic, Wilding, James R, Fortin, Dominique, Domergue-Dupont, Valérie, Novotova, Marta, Ventura-Clapier, Renée, Veksler, Vladimir
Přispěvatelé: Signalisation et physiopathologie cardiaque, Université Paris-Sud - Paris 11 (UP11)-IFR141-Institut National de la Santé et de la Recherche Médicale (INSERM), Institute of Molecular Physiology and Genetics (IMPG), Slovak Academy of Science [Bratislava] (SAS)
Jazyk: angličtina
Rok vydání: 2008
Předmět:
Zdroj: The Journal of Physiology
The Journal of Physiology, Wiley, 2008, 586 (Pt 21), pp.5181-92. ⟨10.1113/jphysiol.2008.157677⟩
ISSN: 0022-3751
1469-7793
DOI: 10.1113/jphysiol.2008.157677⟩
Popis: International audience; Local control of ATP/ADP ratio is essential for efficient functioning of cellular ATPases. Since creatine kinase (CK) activity and mitochondrial content are reduced in heart failure (HF), and cardiomyocyte ultrastructure is altered, we hypothesized that these changes may affect the local energetic control of two major cardiac ATPases, the sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA) and the myosin ATPase. Heart failure was induced by aortic stenosis in rats. Electron microscopy confirmed that failing cardiomyocytes had intracellular disorganization, with fewer contacts between mitochondria and myofibrils. Despite normal SERCA protein content, spontaneous Ca2+ release measurements using Fluo-4 on saponin-permeabilized cardiomyocytes showed a lower SR loading in HF even when endogenous CK and mitochondria were fully activated. Similarly, in permeabilized fibres, SR Ca2+ loading supported by SR-bound CK and mitochondria was significantly reduced in HF (by 49% and 40%, respectively, 43% when both systems were activated, P < 0.05). Alkaline phosphatase treatment had no effect, but glycolytic substrates normalized calcium loading in HF to the sham level. The control by CK and mitochondria of the local ATP/ADP ratio close to the myosin ATPase (estimated by rigor tension) was also significantly impaired in HF fibres (by 32% and 46%, respectively). However, while the contributions of mitochondria and CK to local ATP regeneration were equally depressed in HF for the control of SERCA, mitochondrial contribution was more severely impaired than CK (P < 0.05) with respect to myofilament regulation. These data show that local energetic regulation of essential ATPases is severely impaired in heart failure, and undergoes a complex remodelling as a result of a decreased activity of the ATP-generating systems and cytoarchitecture disorganization.
Databáze: OpenAIRE
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