Changes in serum K+ in asthmatic subjects during exercise

ABSTRACT

Adrenergic mechanisms modulate exercise-induced changes in serum potassium [K+] concentration. Asthmatic subjects had impairment of K + regulation during exercise suggesting that their adrenergic function is impaired. We measured serum K+ and PEF in 25 healthy controls and in 25 asthmatics pre-exercise, at peak exercise and 10 min. post-exercise. Resting K+ was normal for both groups. During exercise, K+ increased in both groups. The values in the asthmatic group, however were higher than controls values. After exercise, K+ returned to baseline in control subjects but remained elevated in asthmatics, supporting the suggestion that their adrenergic function is impaired. The possibility arises that the asthmatics inability to handle an added K+ load accounts for exercise induced bronchoconstriction causing an increase in serum K+, which has recently been shown to potentiate cholinergic activity in the airways