Exercise-induced cardiac mitochondrial reorganization and enhancement in spontaneously hypertensive rats

The myocardium is a highly oxidative tissue in which mitochondria are essential to supply the energy required to maintain pump function. When pathological hypertrophy develops, energy consumption augments and jeopardizes mitochondrial capacity. We explored the cardiac consequences of chronic swimming training, focusing on the mitochondrial network, in spontaneously hypertensive rats (SHR). Male adult SHR were randomized to sedentary or trained (T: 8-week swimming protocol). Blood pressure and echocardiograms were recorded, and hearts were removed at the end of the training period to perform molecular, imaging, or isolated mitochondria studies. Swimming improved cardiac midventricular shortening and decreased the pathological hypertrophic marker atrial natriuretic peptide. Oxidative stress was reduced, and even more interesting, mitochondrial spatial distribution, dynamics, function, and ATP were significantly improved in the myocardium of T rats. In the signaling pathway triggered by training, we detected an increase in the phosphorylation level of both AKT and glycogen synthase kinase-3 beta, key downstream targets of insulin-like growth factor 1 signaling that are crucially involved in mitochondria biogenesis and integrity. Aerobic exercise training emerges as an effective approach to improve pathological cardiac hypertrophy and bioenergetics in hypertension-induced cardiac hypertrophy.