Effects of short- and long-term exercise on urinary cGMP excretion in healthy subjects and in patients with coronary artery disease

The possibility that systemic formation of cyclic guanosine monophosphate ( cGMP) could reflect the level of cardiovascular fitness was investigated. T he relations between physical activity and systemic formation of cGMP were evaluated in healthy volunteers and in patients with coronary artery diseas e (CAD). No significant differences were observed in the basal urinary excr etion of cGMP in highly trained runners, sedentary subjects, and in patient s with CAD, despite the large differences in aerobic exercise training betw een groups. In addition, the basal levels of cGMP in CAD patients failed to increase after a 12-week cardiac rehabilitation program. Short term exerci se, on the other hand, was associated with significant increases in urinary cGMP excretion. A 42-km marathon increased urinary cGMP excretion by 272%. The 15-km race increased urinary cGMP excretion by 330%. In CAD patients, 30 min of supervised exercise on a treadmill, at 80% of patient's maximal h eart rate, induced a 60% increase in urinary cGMP, which returned to preexe rcise levels 90 min after termination of the exercise. Completion of the 12 -week cardiac rehabilitation program improved exercise capacity and the mag nitude of increase in cGMP levels induced by short-term treadmill exercise. Our findings suggest that cGMP increases during and shortly after short-te rm exercise and that the magnitude of the increase seems dependent on the i ntensity of the exercise and on physical fitness. Exercise training in heal thy subjects and in CAD patients enhanced the amount of cGMP produced durin g short-term exercise, which might be responsible for some of the protectiv e cardiovascular actions of exercise. The short half-life of cGMP may expla in why the basal resting levels of cGMP are not appropriate predictors of a subject's physical fitness.