Effect of L-arginine infusion on airway NO in cystic fibrosis and primary ciliary dyskinesia syndrome

Airway nitric oxide concentrations in patients with cystic fibrosis or prim ary ciliary dyskinesia syndrome have been shown to be lower than in healthy subjects. Decreased NO concentrations ma contribute to impaired ciliary cl earance, respiratory tract infections, or obstructive lung disease in these conditions. Nasal and exhaled NO concentrations were compared before and after infusion of 500 mg.kg(-1) L-arginine, the substrate of NO synthases, in 11 cystic f ibrosis (CF) patients, seven primary ciliary dyskinesia (PCD) syndrome pati ents, and 11 control subjects. Baseline nasal and exhaled NO concentrations were significantly low er in b oth CF and PCD syndrome patients than in controls (p<0.01). In controls, th e maximum increase of NO was seen immediately after L-arginine infusion in the upper airways (1.8-fold) and 3 h after the infusion in the lower airway s (1.6-fold. Although NO concentrations also increased significantly in bot h CF (1.9-fold and 1.6-fold, respectively) and PCD syndrome patients (1.4-f old and 1.8-fold. respectively), concentrations remained subnormal compared with baseline values of controls. Pulmonary function remained unchanged in both patient groups. In conclusion, the low airway nitric oxide formation in both cystic fibrosi s and primary ciliary dyskinesia syndrome patients can be augmented by L-ar ginine administration. The finding that pulmonary function remained unchang ed in both conditions may be due to the fact that normalization of airway n itric oxide concentrations could not be achieved.