The effect of partial beta adrenergic blockade on the bronchial response of hay fever subjects to ragweed aerosol

Abstract One hypothesis of the cause of asthma proposes that it is the result of impaired autonomic homeostasis manifested by a partial blockade of the adrenergic beta receptors of cells. This study was undertaken to determine whether a pharmacologically induced beta blockade would increase the bronchial obstruction produced by ragweed aerosol challenge in subjects with hay fever. Ten volunteers with ragweed hay fever were studied before the ragweed season. Each subject was his own control. On each of two separate days the subject was challenged with progressively increased doses of an aerosol of ragweed extract. Before the second challenge, 5 mg. of propranolol, a potent beta adrenergic blocking agent, was given intravenously. A year later, these 5 subjects were again studied with the order of the propranolol and control tests reversed. The response to the aerosol was determined by comparing the volumes of the first second of a forced expiration (FEV 1 ) before and 15 minutes after the aerosol. The mean change in FEV 1 was −13 per cent with the control and −22 per cent with the propranolol. When the order of challenge with propranolol and the control was reversed, these values were much the same, −6 and −19. Partial beta blockade increased the bronchial response to inhaled allergen, a result consistent with the stated hypothesis.