Effects of U46619 (U4; 10-7 M) and acetylcholine (Ach; 10-5 M) in the presence or absence of L-NG-nitro-L-arginine methyl ester (L-NAME) on internal luminal diameter of airway and vessels in whole precision cut lung slices. Panel A shows responses in pulmonary artery and panel B shows responses in bronchi. Measurements were made under basal conditions or after stimulation with U46619 (U4; 10-7 M) or acetylcholine (Ach; 10-5 M) or U4, plus Ach in the presence of L-NAME. The results are the mean +/- the S.E.M. for n = 4–6 experiments. A p-value of < 0.05 was taken as statistically significant, calculated using one sample t-test and denoted by *.