Interaction of Glucocorticoids and Bronchodilators on Isolated Guinea Pig Tracheal and Human Bronchial Smooth Muscle1–3

Recent investigations indicate that glucocorticoids are capable of enhancing the responses to catecholamines on vascular smooth muscle. The present study was undertaken to compare the interaction of three glucocorticoids (hydrocortisone sodium succinate, methyl prednisolone sodium succinate, and dexamethasone phosphate) with a series of catecholamine and noncatecholamine beta sympathomimetic bronchodilators on guinea pig tracheal and human bronchial smooth muscle. Log dose-response lines were obtained for isoproterenol (ISO), epinephrine (EPI), norepinephrine (NOR), salbutamol (SAL), and metaproterenol (META) in the absence and presence of varying concentrations of three different glucocorticoids. Hydrocortisone and methyl prednisolone potentiated the responses to all beta agonists on the guinea pig trachea. The degree of potentiation was greatest with ISO, significantly less with EPI, and much less with NOR, SAL, and META. Dexamethasone, however, produced only minimal alterations of the responses to the ...