INCREASED CONJUGATED DOPAMINE IN PLASMA AFTER EXERCISE TRAINING

  • 1 January 1984
    • journal article
    • research article
    • Vol. 104  (1) , 77-85
Abstract
To evaluate the effect of endurance exercise on plasma catecholamines, 8 dogs (group T) were exercise trained by treadmill running for 8 wk. Six sedentary dogs constituted a nontrained control group (group NT). Heart rate response to a graded submaximal stress test was reduced in group T dogs (P < 0.05), but mean resting aortic blood pressure (NT, 84 .+-. 5 mm Hg; T, 82 .+-. 4 mm Hg) and heart rate (NT, 87 .+-. 1 bpm [beats per minute]; T, 84 .+-. 2 bpm) were unchanged by exercise and no cardiac hypertrophy occurred after exercise. Plasma norepinephrine [NE] and epinephrine [E] levels were reduced in group T at rest and during a fixed exercise workload. Plasma conjugated dopamine showed a marked increase in group T dogs (NT, 1398 .+-. 130 pg/ml; T, 11,346 .+-. 1291 pg/ml; P < 0.01) at rest and no change in conjugated dopamine occurred in either group after short-term exercise stress. No intergroup differences were noted in resting coronary flow or coronary arteriovenous O2, or in myocardial O2 consumption. The data verify previous findings of lower plasma levels of NE and E after training and indicate that a marked rise in conjugated dopamine occurs after training. NE and E metabolism evidently is shifted toward conjugated dopamine by exercise training, thereby reducing active catecholamines in plasma, but retaining a large pool of usable metabolite.