Effect of growth hormone therapy on nitric oxide formation in cystic fibrosis patients

¹ Children's Hospital, University of Duisburg-Essen, Essen, Germany; and Dept of paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
² Dept of paediatric Endocrinology, Charité University Hospital, Humboldt University, Berlin, Germany
³ Children's Hospital, University of Duisburg-Essen, Essen, Germany

^* To whom correspondence should be addressed. E-mail: hartmut.grasemann{at}sickkids.ca.

	Abstract

Airway nitric oxide production is decreased in cystic fibrosis. As growth hormone therapy has been shown to increase nitric oxide production in growth hormone deficiency, it may also affect nitric oxide production in patients with cystic fibrosis.

To study the effect of growth hormone therapy on systemic and airway nitric oxide formation in patients with cystic fibrosis.

Nitric oxide metabolites in serum and urine, amino acid concentrations in serum and sputum, as well as exhaled nitric oxide was measured in children with cystic fibrosis before, during and after one year of treatment with human growth hormone.

Nitric oxide metabolite concentrations increased significantly in serum and urine during the treatment period. Serum amino acids concentrations including L-arginine, the substrate for nitric oxide synthases also increased during treatment. The systemic bio-availability of L-arginine for nitric oxide synthases, expressed as ratio of L-arginine/L-ornithine+lysine, remained unchanged. In contrast, L-arginine concentrations in sputum decreased significantly during growth hormone treatment, as did exhaled nitric oxide levels.

Treatment with growth hormone in children with cystic fibrosis decreases exhaled nitric oxide by reducing the concentration of L-arginine in the airways.