Cardiac anti-remodelling effect of aerobic training is associated with a reduction in the calcineurin/NFAT signalling pathway in heart failure mice

AUTOR(ES)

Oliveira, R S F

FONTE

Blackwell Science Inc

RESUMO

Cardiomyocyte hypertrophy occurs in response to a variety of physiological and pathological stimuli. While pathological hypertrophy in heart failure is usually coupled with depressed contractile function, physiological hypertrophy associates with increased contractility. In the present study, we explored whether 8 weeks of moderate intensity exercise training would lead to a cardiac anti-remodelling effect in an experimental model of heart failure associated with a deactivation of a pathological (calcineurin/NFAT, CaMKII/HDAC) or activation of a physiological (Akt–mTOR) hypertrophy signalling pathway. The cardiac dysfunction, exercise intolerance, left ventricle dilatation, increased heart weight and cardiomyocyte hypertrophy from mice lacking α2A and α2C adrenoceptors (α2A/α2CARKO mice) were associated with sympathetic hyperactivity induced heart failure. The relative contribution of Ca2+–calmodulin high-affinity (calcineurin/NFAT) and low-affinity (CaMKII/HDAC) targets to pathological hypertrophy of α2A/α2CARKO mice was verified. While nuclear calcineurin B, NFATc3 and GATA-4 translocation were significantly increased in α2A/α2CARKO mice, no changes were observed in CaMKII/HDAC activation. As expected, cyclosporine treatment decreased nuclear translocation of calcineurin/NFAT in α2A/α2CARKO mice, which was associated with improved ventricular function and a pronounced anti-remodelling effect. The Akt/mTOR signalling pathway was not activated in α2A/α2CARKO mice. Exercise training improved cardiac function and exercise capacity in α2A/α2CARKO mice and decreased heart weight and cardiomyocyte width paralleled by diminished nuclear NFATc3 and GATA-4 translocation as well as GATA-4 expression levels. When combined, these findings support the notion that deactivation of calcineurin/NFAT pathway-induced pathological hypertrophy is a preferential mechanism by which exercise training leads to the cardiac anti-remodelling effect in heart failure.

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