Figure 6.

The concentration–response curves for carbachol (A,B) and for isoprenaline (C,D) in the absence or presence of antagonists in human segmental (left) and subsegmental bronchi (right). Upper panels: as described in the Methods, the maximum contraction in the first concentration–response curve for carbachol was taken as 100% in each preparation, and the antagonist was applied for 40 min before and during the second concentration–response curve in the same preparation. Lower panels: papaverine (100 µM)-induced relaxation was taken as 100%. The β-adrenoceptor antagonist was applied for 40 min before and during the concentration–response curve for isoprenaline in each preparation. Control means time control without antagonist treatment, which was carried out in parallel with antagonist experiments. Means ± SEM of four to six preparations isolated from four individuals are presented.