DIFFERENTIAL EFFECTS OF THE CALCIUM‐ANTAGONISTIC VASODILATORS, NIFEDIPINE AND VERAPAMIL, ON THE TRACHEAL MUSCULATURE AND VASCULATURE OF THE DOG

Abstract

In anaesthetized dogs the trachea in situ was perfused arterially with blood, and drugs were injected intraarterially. Isoprenaline and the calcium-antagonistic vasodilators, nifedipine and verapamil, increased tracheal blood flow and decreased resting tone of the trachea. Isoprenaline was equi-effective in producing tracheal vasodilatation and tracheal dilatation. The two calcium-antagonistic vasodilators were less effective tracheal dilators than tracheal vasodilators.