Influence of alpha-adrenoceptor blockade on antigen- and propranolol-induced bronchoconstriction in guinea-pigs in vivo. 
1.  Beta-adrenoceptor antagonists, such as propranolol, can provoke severe bronchoconstriction only in asthmatic subjects.  Recently, we developed a guinea-pig model of propranolol-induced bronchoconstriction (PIB) and the purpose of this study was to investigate the role of alpha-adrenergic nerve pathways in this reaction.  2.  Phentolamine administered after an antigen challenge did not inhibit PIB; however, its administration before the antigen challenge significantly inhibited the antigen-induced bronchoconstriction and also bronchoconstriction induced by methacholine inhalation.  3.  We conclude that the alpha-adrenergic nerve system is not involved in the development of PIB following allergic reaction in our guinea-pig model.