Inducción transcripcional del gen de la sintasa endotelial del óxido nítrico y formación de peroxinítrito en el endotelio vascular en respuesta a Ciclosporina A

Tesis doctoral inédita leída en la Universidad Autonoma de Madrid, Facultad de Medicina, Departamento de Medicina, 18 de Diciembre de 200

Na+ controls hypoxic signalling by the mitochondrial respiratory chain

All metazoans depend on O2 delivery and consumption by the mitochondrial oxidative phosphorylation (OXPHOS) system to produce energy. A decrease in O2 availability (hypoxia) leads to profound metabolic rewiring. In addition, OXPHOS uses O2 to produce reactive oxygen species (ROS) that can drive cell adaptations through redox signalling, but also trigger cell damage1–4, and both phenomena occur in hypoxia4–8. However, the precise mechanism by which acute hypoxia triggers mitochondrial ROS production is still unknown. Ca2+ is one of the best known examples of an ion acting as a second messenger9, yet the role ascribed to Na+ is to serve as a mere mediator of membrane potential and collaborating in ion transport10. Here we show that Na+ acts as a second messenger regulating OXPHOS function and ROS production by modulating fluidity of the inner mitochondrial membrane (IMM). We found that a conformational shift in mitochondrial complex I during acute hypoxia11 drives the acidification of the matrix and solubilization of calcium phosphate precipitates. The concomitant increase in matrix free-Ca2+ activates the mitochondrial Na+/Ca2+ exchanger (NCLX), which imports Na+ into the matrix. Na+ interacts with phospholipids reducing IMM fluidity and mobility of free ubiquinone between complex II and complex III, but not inside supercomplexes. As a consequence, superoxide is produced at complex III, generating a redox signal. Inhibition of mitochondrial Na+ import through NCLX is sufficient to block this pathway, preventing adaptation to hypoxia. These results reveal that Na+ import into the mitochondrial matrix controls OXPHOS function and redox signalling through an unexpected interaction with phospholipids, with profound consequences in cellular metabolism

Transcatheter Mitral Repair for Functional Mitral Regurgitation According to Left Ventricular Function: A Real-Life Propensity-Score Matched Study

Background: Transcatheter mitral valve repair (TMVR) could improve survival in functional mitral regurgitation (FMR), but it is necessary to consider the influence of left ventricular ejection fraction (LVEF). Therefore, we compare the outcomes after TMVR with Mitraclip® between two groups according to LVEF. Methods: In an observational registry study, we compared the outcomes in patients with FMR who underwent TMVR with and without LVEF <30%. The primary endpoint was the combined one-year all-cause mortality and unplanned hospital readmissions due to HF. The secondary end-points were New York Heart Association (NYHA) functional class and mitral regurgitation (MR) severity. Propensity-score matching was used to create two groups with the same baseline characteristics, except for baseline LVEF. Results: Among 535 FMR eligible patients, 144 patients with LVEF <30% (group 1) and 144 with LVEF >30% (group 2) had similar propensity scores and were included in the analyses. The primary study endpoint was significantlly higher in group 1 (33.3% vs. 9.4%, p = 0.002). There was a maintained improvement in secondary endpoints without significant differences among groups. Conclusion: FMR patients with LVEF <30% treated with MitraClip® had higher mortality and readmissions than patients with LVEF ≥30% treated with the same device. However, both groups improved the NYHA functional class and MR severity