Figure 1.

Cardioprotective signalling molecules activated by exercise. Short-term and long-term exercise training has been shown to increase the expression and activity of components of the endogenous antioxidant defense system (catalase, SODs), increase the expression of heat shock proteins (HSPs), activate ATP-sensitive potassium (K_ATP) channels, and increase the expression and activity of endothelial nitric oxide synthase (eNOS) resulting in an increase in nitric oxide (NO) levels. Although all of these molecules have been associated with the cardioprotection afforded by exercise training, studies have shown that endogenous antioxidants and HSPs are not necessary for the observed cardioprotection, whereas K_ATP channels and eNOS are necessary.