CONICET | Buscador de Institutos y Recursos Humanos

Introduction: Fabry disease is a genetic X-linked lysosomal storage disorder caused by a deficiency in the enzyme alpha-galactosidase A that affects, inter alia, to cardiac tissue. Clinical evidence indicates that cardiac arrhythmias are common in older patients withFabry disease and these have a significant impact on patient survival. The present study assesses calcium handling proteins and intracellular calcium dynamics in hearts from Fabry (Fb) and the corresponding wild-type (WT) mice to determine whether there is a potential arrhythmogenic substrate at the cellular level responsible for triggering cardiac arrhythmias in Fabry disease. Methods: Animals: A murine model of Fabry disease (alpha-galactosidase A knockout mice) and the corresponding WT mice were used. Homogenates from freshly isolated and immediately frozen hearts from WT and Fb mice were used for western blotting utilizing specific antibodies for assessing calcium handling proteins. Isolated myocytes from WT and Fb mice were employed for evaluating contractility, intracellular calcium transients and sarcoplasmic reticulum (SR) calcium content. Confocal experiments in isolated myocytes were performed to assess calcium sparks and waves. Results: Hearts from Fb mice were hypertrophic, as previously described and exhibited a similar protein expression level of CaMKII, NCX, PCaMKII, SERCA2a and RyR2. However, there was a significantly increased phosphorylation of PKA and CaMKII sites of the RyR2 (PSer2808 and PSer2814) in Fb respect to WT mice (193.3±22.8% vs. 100.0±12.4%, 232.5±55.8% vs. 100.0±14.8%, respectively). This increase in RyR2 phosphorylation was not accompanied by a significant alteration in SR calcium content but was associated with a significant increase in calcium sparks and waves, both in the absence and presence of isoproterenol, with respect to WT mice.