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Hambrecht, Rainer1

Medicine & Science in Sports & Exercise: May 2003 - Volume 35 - Issue 5 - p S2
Nitric Oxide: Role in Combating Disease

1Heart Center – University of Leipzig, Leipzig, Germany

Exercise training has well-established beneficial effects on symptoms and myocardial perfusion in patients with coronary artery disease (CAD). Regression of coronary artery stenosis and improvement of collateralization have been suggested as potential mechanisms. However, angiographic techniques have so far failed to document any significant increase in coronary collaterals at rest. Although net regression of stenotic lesions may be achieved in high intensity exercise training it is unlikely that in causes the significant improvement in myocardial perfusion which is seen much earlier than plaque regression. Myocardial perfusion and angina levels improve within weeks after the initiation of training programs – much more rapidly than explained by morphologic changes. Within the last decade endothelial dysfunction has been identified as a trigger of myocardial ischemia. The impaired production of endothelium-derived nitric oxide (NO) in response to acetylcholine and flow leads to paradoxic vasoconstriction and exercise-induced ischemia. The novel tools to examine coronary endothelial function in vivo and in vitro have now made it clear, that exercise training enhances myocardial perfusion by increasing both eNOS and ecSOD expression, which attenuates the premature breakdown of NO by ROS. These increases in both local NO production and half-life improve endothelium-dependent vasodilation in response to flow or acetylcholine. It is reasonable to suppose that these functional changes occur rather rapidly after the initiation of an exercise training program – although no studies are available on their precise time course. Anatomic changes like augmentation of the capillary bed and slowing of the progression of coronary atherosclerosis will require more extended periods of training. Recently, first reports about a possible association between endothelial dysfunction and the frequency of clinical events have been published. If it turns out to be an independent prognostic marker exercise training may be promoted from a symptomatic intervention to a preventive strategy with long-term prognostic benefits.

©2003The American College of Sports Medicine