Antagonism by beta-adrenoceptor blocking agents of the antianaphylactic effect of isoprenaline.

1. beta-Adrenoceptor blocking agents antagonized the inhibitory (antianaphylactic) effect of isoprenaline on antigen-induced histamine release in isolated, passively sensitized, human lung and actively sensitized guinea-pig lung suggesting that the effect is exerted through beta-adrenoceptors. No antagonism was obtained with the human allergic leucocyte preparation.2. The antianaphylactic effect of isoprenaline was antagonized not only by propranolol but also by the ;selective' beta-adrenoceptor blocking agents, practolol and butoxamine.3. The classification of beta-adrenoceptors is discussed. Certain similarities between antianaphylactic and lipolytic beta-adrenoceptors are noted.