Fig. 1.

Nitric oxide (NO) expression in sputum samples from cystic fibrosis (CF) patients with chronic Pseudomonas aeruginosa lung infection. (a) Mean percentage of cells positive for 4-amino-5-methylamino-2′,7′-difluorofluorescein diacetate (DAF-FM) fluorescence in untreated sputum and in sputum treated with 2 mM NG-monomethyl-L-arginine (L-NMMA) (P < 0·002, n = 8). Statistical analysis was performed by Wilcoxon's signed-rank test. (b) Representative example of intracellular DAF-FM fluorescence (FL h1- height) in untreated sputum cells (blue histogram) and L-NMMA-treated sputum cells (red histogram). (c) Visualization of NO production by fluorescence microscopy (green colour) of cells stained with (DAF-FM) in untreated sputum and (d) sputum treated with 2 mM L-NMMA to inhibit nitric oxide synthase (NOS).