Sensitization of the calf tracheal muscle to β-adrenergic bronchospasmolytics by β-haloalkylamines and cocaine

The mechanism of sensitization of the isolated calf tracheal muscle to β-adrenergic agents caused by the β-haloalkylamines dibenamine and phenoxybenzamine was studied. The results obtained strongly suggested that this sensitization, which has the characteristics of an irreversible change, was not connected with the α-adrenolytic action of these β-haloalkylamines and that no induced change in the structure of the β-adrenergic receptors was involved. Further it was concluded that the mechanism behind the sensitizing action in question whetessentially different from that responsible for the sensitization caused by cocaine. As yet the question whether the degree of the sensitization is linked with the potency of the β-adrenergic agonist given, has to be left open, although some indications were obtained which argue in favour of this hypothesis.