The beta-adrenoceptors of the lung mediating inhibition of antigen-induced histamine release.

The beta-adrenoceptor stimulants, isoprenaline (IPR), orciprenaline (OPR), terbutaline (TRB), and ITP were studied for effects on antigen-induced release of histamine from guinea-pig lung tissue and for effects on guinea-pig isolated trachea and heart. The order of potency for the agents in the four funct-ons studied were: (a) inhibition of histamine release, IPR greater than OPR approximately equal to TRB greater than ITP equal 0; (b) heart stimulation, chronotropic effect, IPR greater than OPR greater than ITP approximately equal to TRB; (c) heart stimulation, inotropic effect, IPR greater than OPR greater than ITP greater than TRB; (d) trachea relaxation: IPR greater than TRB greater than OPR greater than ITP. These findings suggest that the beta-adrenoceptors mediating inhibition of antigen-induced release of histamine are more related to those mediating trachea relaxation (beta2) than those mediating cardiac stimulation (beta1).