Alpha-Adrenergic Receptors in the Human Lung

Abstract

The whole-body plethysmograph was used to study airway conductance (Gaw/Vgt) in humans after adrenergic agents, nebulized in a propylene glycol and water vehicle, were inhaled. Ten young males free of pulmonary or other disease were given the vehicle alone as well as the α stimulant, methoxamine. Gaw/Vgt increased slightly after the vehicle was administered. However, in all 10 subjects, a decrease was noted after they had received methoxamine alone. The α blocker, phentolamine, was given to 7 additional subjects; it produced a slight increase in Gaw/Vgt. When blocker and α stimulant were given together, the previous decrease seen with methoxamine alone was abolished. Finally, in 3 subjects, a dose-response curve was obtained, showing a steady but mild decrease in Gaw/Vgt (to a maximum of 10% loss) as doses of methoxamine were increased. These findings--(a) highly significant decrease in Gaw/Vgt after an inhaled α stimulant, (b) prevention of this by the concomitant inhalation of an α blocker, and (c) demonstration of a dose-related drug effect--suggest the presence of α-adrenergic receptors in the human tracheobronchial tree.