Effect of dihydroergotoxine on activities of beta-receptor stimulators.

The effect of dihydroergotoxine (DET), an alpha-receptor blocker, on the bronchodilating effect of various beta-receptor stimulators was examined using the isolated guinea-pig tracheal smooth muscle. Relaxation of isolated guinea-pig tracheal smooth muscle with isoproterenol hydrochloride, salbutamol hemisulfate and clorprenaline hydrochloride, was markedly increased by continous infusion of DET. This result may suggest that DET, an alpha-receptor blocker, can be used together with bronchodilators such as beta-receptor stimulator for the treatment of various chronic obstructive pulmonary diseases.