Effect of beta-adrenergic agonists aerosolized by freon propellant on tracheal mucous velocity and cardiac output

The present study was designed to assess the effects of two beta-adrenergic agonists, isoproterenol sulfate and carbuterol hydrochloride, and aerosolized Freon propellant (a mixture of Freon II, Freon 12, and Freon 114) on tracheal mucous velocity and cardiac output in anesthetized dogs. Five groups of ten animals each received the following dosages of aerosols: Freon, 20 puffs; isoproterenol, four puffs; carbuterol, four puffs; isoproterenol, 20 puffs; and carbuterol, 20 puffs. The puff was delivered by a standard metered aerosol; each puff of isoproterenol spray contained 75 mug of isoproterenol sulfate, and each puff of carbuterol spray contained 100 mug of carbuterol hydrochloride. Tracheal mucous velocity was not changed by receiving Freon, but administration of both isoproterenol and carbuterol caused a significant increase in this measurement, with peak increases ranging from 74 to 111 percent above control values. The duration of action for four and 20 puffs of isoproterenol and for four puffs of carbuterol was two hours. Twenty puffs of carbuterol increased tracheal mucous velocity for three hours. Administration of carbuterol effected a slightly larger increase in cardiac output than isoproterenol. The duration of action for the increased cardiac output was shorter than the duration of action for the increased tracheal mucous velocity. These studies indicate that beta-adrenergic agonists may have an important role in improving mucous transport in patients with chronic obstructive pulmonary disease in whom mucociliary clearance is depressed.