We and others have demonstrated that inhibition of NOX2 prior to exercise abolishes the infarct salvage of early and late phases of exercise cardioprotection (Sanchez et al. 2008; Frasier et al. 2013).
Studies in favor of this hypothesis have shown that administration of antioxidants prior to exercise abolishes infarct salvage (Yamashita et al. 1999; Akita et al. 2007) and prevents exercise-induced improvements in cardiac performance (Nelson et al. 2011).
Others have observed an increase in iNOS activity following an acute bout of exercise, and when an iNOS inhibitor was administered prior to I/R the antiarrhythmic effect of exercise was abolished (Babai et al. 2002).
In all, these data together with data from our current study suggest a link between insulin resistance and a defective regulation of PGC-1α and downstream mitochondrial proteins in response to exercise, so that under conditions of severe insulin resistance, the induction of PGC-1α in response to exercise is abolished.
They demonstrated that administration of TNF-α and IL-1 antibodies prior to a single exercise bout abolished the early- and late-windows of cardioprotection.
Following exercise, there is an increase in eNOS activation and NO metabolites (Akita et al. 2007; Calvert et al. 2011), and when eNOS is genetically knocked out, the infarct sparing effects after seven days of exercise is abolished (Akita et al. 2007).
No study has established that breath-by-breath control of PaCO2 nor the hyperpnea of exercise is obviously abolished after carotid chemodenervation.
On the other hand, when ROS production was prevented in rats, up-regulated expression of important enzymes associated with cell defense (like SOD) and adaptation to exercise were also abolished [ 22, 23].
This proposal predicts that the hyperventilation should be abolished during exercise by unloading the carotid chemoreceptors with sufficient hyperoxia, but this has not yet been demonstrated [ 67 ].
However, several studies have reported that the cardioprotective effect exerted by exercise against reperfusion injuries can be abolished when antioxidants are administrated during exercise, indicating the crucial role of ROS signaling in exercise-induced preconditioning pathways [ 53– 53].
