Plasma catecholamines during exercise-induced bronchoconstriction in bronchial asthma

ABSTRACT Plasma levels of adrenaline and noradrenaline during and after submaximal exercise in patients with bronchial asthma were investigated. Three groups were studied comprising 10 patients with exercise-induced bronchoconstriction (EIB), 1Oasthmatic patients without EIB and four normal control subjects. Plasma catecholamines were measured at rest, at the end of exercise, and five and 15 minutes after exercise. Changes in airway resistance were assessed by measuring peak expiratory flow rate. Significant differences in catecholamine levels between reacting and non-reacting patients were found. In 10 patients developing EIB adrenaline and noradrenaline levels had risen significantly by the end of exercise and remained elevated up to the fifth minute of recovery. The rise in catechola-mine levels in non-reacting asthmatics was insignificant. In control subjects noradrenaline had increased significantly by the end of exercise. Despite many years of investigation some aspects of exercise-induced bronchoconstriction (EIB) remain unclear. Its mechanism is not yet known nor are the reasons for its appearance after com-pletion of exercise rather than during it. It is well known that plasma catecholamine levels increase during physical exercise. ' A rise in noradrenaline level depends on the work performed in relation to the maximal oxygen uptake.2 3 Adrenaline level rises only at a very high workload.4 6 Adrenaline is one of the most potent endogen-ous bronchodilators. Noradrenaline induces a constriction of bronchial smooth muscle. Respec-tive levels and reciprocal relations between adrenaline and noradrenaline during and after physical exercise in patients with bronchial asthma may influence the time of onset and the course of EIB. The aim of this study was to investigate the changes in catecholamine levels during and after exercise in asthmatic patients with and without EIB. Method