Abstract 1626: Exercise Training Has Protective Effects in Acute Cardiac Overload by Preventing Apoptosis and Nf-kB Activation
Introduction: Cardiac overload is an important stimulus for triggering HF. We hypothesized that exercise training (ExT) could positively influence the early cardiac adaptation to overload by preserving myocardial integrity and modulating the triggers of pathways associated with pathological cardiac remodeling.
Material and Methods: Male Wistar rats were randomized in 3 groups:
Exercise Overload (Ex+Ov; n=5; 14 week-ExT and acute pressure overload at the end of the study),
Control (CT; n=5; no exercise and no overload) and
Control Overload (CT+Ov; n=5; overload in non exercised animals). At the end of the ExT protocol, animals were prepared for hemodynamic instrumentation with tip micromanometer pressure catheters.
An acute pressure overload (APO) was induced by constricting the descending aorta (60% LVPmax elevation) for 120 min. Samples from cardiac tissue were prepared for Light (LM) and Transmission Electron Microscopy (TEM) and immunohistochemistry (cleaved caspase-3 and Nf-kB).
Results: In comparison with CT group, CT+Ov animals presented intracellular edema and mitochondrial swelling in both ventricles. Regarding hemodynamic function, alterations were limited to LV, which showed diastolic dysfunction (Tau=13±8vs15±3vs22±9ms; CT, CT+Ov at 0 min and CT+Ov at 120 min of APO, respectively). Conversely, in Ex+Ov group, APO resulted in mild signs of cardiac interstitial edema in both ventricles, with no detectable LV or RV dysfunction. Regarding apoptosis, cleaved caspase-3 was detectable only in LV of CT+Ov group. In relation to Nf-kB, LV of CT+Ov group presented higher expression levels as compared to Ex+Ov group. There was no significant expression of caspase-3 or Nf-kB in RV of both groups.
Conclusion: The present study shows that apoptosis and Nf-kB pathways are activated as early as 2 hours after LV APO and that ExT seems to be effective in reducing their activation. We demonstrated that contrarily to sedentary animals, ExT preserved the ultra-structure of both ventricles. These findings suggest that exercise training has an important protective role in the modulation of the early cardiac response to pressure overload.