Effect of glucocorticoids on the response of airway smooth muscle to catecholamine and resorcinol β-agonists

The influence of hydrocortisone (11β,17α,21-trihydroxy-pregn-4-ene-3,20-dione) or of methylprednisolone (6α-methyl-11β,17α-21-trihydroxy-1,4-pregnadiene-3,20-dione) on the response of airway smooth muscle to a variety of β-adrenergic bronchodilators was evaluated using incubated guinea pig tracheal rings, preconstricted with histamine. The adrenergic agonists chosen for this study included the nonselective β1- and β2-catecholamine, isoproterenol, the selective β2-catecholamine, rimiterol, and the selective β2-resorcinols, fenoterol and terbutaline. When the incubated rings were pretreated with 10–50 μg/mL of the steroids, there was a significant enhancement in smooth muscle sensitivity and reactivity to rimiterol and isoproterenol. Tracheal response to fenoterol or terbutaline, on the other hand, was not altered by the glucocorticoids. When used alone, neither steroid exerted an inotropic influence on the tracheal smooth muscle. The results of our study indicate that glucocorticoid enhancement of adrenerg...