Catecholamines, Adrenergic Receptors and Exercise Capacity in Trained Subjects and in Coronary Heart Disease

Summary

An activation of the sympathetic nervous system can be observed, dependent on decreasing cardiac pump capacity and decreasing exercise capacity in coronary heart disease patients. The sympathetic activation contributes to an uneconomical functioning of the damaged heart; this activation is the result and not the cause of the disease. In end-stage IV coronary heart disease, increasing exhaustion of the sympathetic system is probable with impaired neurotransmitter synthesis, storage, re-uptake and homologous desensitization of target organs. As we know from training methods, improvement in the aerobic exercise capacity — beside an increase in vagal tone — reduces sympathetic activity. This mechanism can also be observed in physical therapy of suitable heart patients, hemodynamically stage I and II. The extent is, of course, much lover, only marginal in part, or not givem, dependent on the remaining exercise capacity and the course of their disease. Thus, after one year of physical therapy, there was a mean decrease in the lactate, noradrenaline and adrenaline responses at same exercise levels with a reduction in the double product; consequently, an economization of cardiac work, which on the average favored a 25% increase in exercise capacity without direct improvement of coronary circulation or myocardial function.