Mapping of Adrenergic Receptors in the Trachea by Autoradiography

Abstract

Distribution was investigated of adrenergic receptors in ferret trachea using autoradiography. [3H]Dihydroalprenolol, used to identify .beta.-adrenoceptors, revealed a high density of specific binding sites over surface epithelium and submucosal glands, with less labeling of smooth muscle. [3H]Prazosin labeling showed that .alpha.1-receptors were numerous in glands and epithelium, but sparse in smooth muscle. Comparison of adrenergic receptor densities in tracheal sections from the same animals showed a rank order for submucosal glands of .alpha.1 > .beta., for epithelium .beta. > .alpha.1 and for smooth muscle .beta. > .alpha.1. Within the submucosal glands, .alpha.1-and .beta.-adrenergic receptors were differentially distributed, with .alpha.1-receptors being significantly more numerous over serous than mucous cells and .beta.-receptors being significantly more numerous over mucous than serous cells. This technique provides insight into adrenergic regulation of airway function and should be useful in investigations of how relative receptor densities may be altered in disease.