Plasma adenosine concentration increases during exercise: a possible contributing factor in exercise-induced bronchoconstriction in asthma.

We investigated whether the level of plasma adenosine (ADO) changed during exercise and whether this could be related to exercise-induced bronchoconstriction. Baseline levels of ADO did not differ, but exercise resulted in higher ADO in patients with asthma than in healthy subjects (86 +/- 35 vs 59 +/- 16 nmol/L; P <.001). In patients with asthma, the increase in ADO was related to decreases in FEV(1) (r (2) = 0.475; P <.05) and SaO(2) (r (2) = 0.693; P <.05). These data suggest that adenosine might be involved in the development of exercise-induced bronchoconstriction.