Effects of U46619 (10-7 M) and acetylcholine (Ach; 10-5 M) on internal luminal diameter of airway and vessels in whole precision cut lung slices. A; Tissue under control (basal conditions) bathed in medium alone. B; Tissue after 6 min stimulation with U46619. C; Tissue after 5 min stimulation with U46619 and acetylcholine. The images are representative of those used in the pooled data shown in Figure 2.