EFFECTS OF TRAPIDIL ON MUSCULATURE AND VASCULATURE OF THE DOG TRACHEA INSITU

  • 1 January 1981
    • journal article
    • research article
    • Vol. 252  (2) , 307-312
Abstract
In anesthetized dogs the trachea in situ was perfused with blood through the cannulated cranial thyroid arteries. The effects of trapidil on tracheal musculature and vasculature were assessed in comparison to those of isoproterenol and theophylline. All drugs were injected intra-arterially. Isoproterenol (0.03-0.3 .mu.g), trapidil (10-300 .mu.g) and theophylline (30-300 .mu.g) all produced an increase in tracheal blood flow (tracheal vasodilatation) and a decrease in the tracheal intraluminal pressure elevated by neostigmine (tracheal dilatation). In high doses the 3 drugs all produced maximal tracheal dilatation. Dose-response curves for tracheal vasodilatation to the 3 drugs were all parallel together, and trapidil was .apprx. 2700 .times. less potent than isoproterenol and .apprx. 3 .times. more potent than theophylline on a weight basis in producing tracheal vasodilatation. Dose-response curves for tracheal dilatation to the 3 drugs were also parallel together and trapidil was .apprx. 880 .times. less potent than isoproterenol and .apprx. 3 .times. more potent than theophylline on a weight basis. When compared to isoproterenol, trapidil was .apprx. 3 .times. more effective on tracheal musculature than on tracheal vasculature and theophylline resembled trapidil. Apparently, trapidil can also be used as a bronchodilator.