Desensitization of the beta-adrenergic receptor on leucocytes after long-term oral use of a beta-sympathicomimetic; its effect on the beta-adrenergic blockade hypothesis of Szentivanyi.

Development of beta-receptor desensitization in leucocytes of asthmatics and normals during oral therapy with terbutaline was established by means of in vitro stimulation with terbutaline and isoproterenol. This desensitization disappeared about one week after oral therapy was discontinued. In addition no difference in stimulation pattern, measured as increase in intracellular c-AMP content, was determined between asthmatics and normals when both were not receiving therapy. Even when the asthmatics showed strong bronchial hyperreactivity no difference was found. These results do not support the beta-adrenergic blockade hypothesis of Szentivanyi.