Effect of ACTH on the relaxation of guinea pig trachea with various bronchodilators.

The effect of ACTH on the actions of various bronchodilators was examined using the isolated guinea pig tracheal smooth muscle. Relaxing effects of isolated guinea pig tracheal smooth muscle with 1-isoproterenol hydrochloride, salbutamol hemisulfate, hexoprenaline hydrochloride and epinephrine except prostaglandin E2 and aminophylline were markedly potentiated by combining ACTH. These results may suggest that ACTH has a direct effect on guinea pig tracheal smooth muscle by potentiating the actions of various beta-receptor stimulators.