[Effect of corticosteroids on the action of sympathomimetics]

Corticosteroids restore the bronchial responsiveness to beta-adrenergic stimulants in man. This has been shown both in severe asthmatic patients and in normal subjects, rendered insensitive by artificial means. On the contrary, in patients with bronchial asthma who have airways reactive to beta-adrenergic stimulants, the combination of corticosteroids and sympathicomimetics results in an additive effect of their bronchodilating capacity. Animal models, both in vivo and in vitro, show the same type of interaction between corticosteroids and beta-adrenergic stimulants. The mechanism by which corticosteroids restore the bronchial sensitivity to beta-adrenergic stimulation is not completely understood. Several mechanisms may be involved such as increased agonist binding, decreased receptor turn-over, increased uncoupling between receptor and adenylcyclase, decreased extraneuronal uptake, decreased COMT-activity. The relevance of the influence of corticosteroids on the metabolism of membrane phospholipids remains highly speculative.