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 br onchoconstriction only in asthmatic subjects. Recently, we developed a guin ea-pig model of propranolol-induced bronchoconstriction (PIB) and the purpo se of this study was to investigate the role of alpha-adrenergic nerve path ways in this reaction. 2 Phentolamine administered after an antigen challenge did not inhibit PIE; however, its administration before the antigen challenge significantly inh ibited 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 PIE following allergic reaction in our guinea-pig model.