The role of the adrenal glands and of α- and β-adrenergic receptors in bronchodilatation of guinea-pig lungs in vivo

Adrenaline, aminophylline, isoprenaline, noradrenaline, papaverine and phenylephrine exerted non-specific bronchodilator effects in guinea-pig lungs in vivo. The descending order of bronchodilator potency was isoprenaline > adrenaline > noradrenaline > phenylephrine. These agents also exerted a bronchoconstrictor effect, the descending order of bronchoconstrictor potency being phenylephrine > noradrenaline > adrenaline > isoprenaline. Bronchodilator activity could be antagonized by either α- or β–adrenergic receptor antagonists. The bronchodilator action of aminophylline, papaverine, phenylephrine and noradrenaline was partly mediated via the adrenal gland.