Type I nitric oxide synthase in the human lung is predominantly expressed in capillary endothelial cells.
Nitric oxide (NO) has important functions in the regulation of pulmonary smooth muscle tone. In the human lung, published data on the expression and distribution of neuronal nitric oxide synthase (NOS-I) are contradictory. The aim of this study, therefore, was to determine the predominant cells expressing NOS-I in the human lung. Immunofluorescence double staining techniques were applied to normal human lung tissue using established monospecific antibodies directed against NOS-I. Suprisingly, capillary endothelial cells in the alveolar septa were identified as the major sites of NOS-I expression. Neither alveolar nor bronchiolar epithelium, nor the alveolar macrophages, expressed NOS-I. These results indicate that the predominant sites of NOS-I expression in the human lung are confined to non-neuronal, i.e. capillary endothelial cells and suggest a role for NO in the regulation of pulmonary endothelial cell permeability.
Lührs
Hardi
H
Department of Medicine, University of Würzburg, J.-Schneider-Str. 2, 97080 Würzburg, Germany. h.luehrs@medizin.uni-wuerzburg.de
Papadopoulos
Thomas
T
Schmidt
Harald H H W
HH
Menzel
Thomas
T
D002196:Capillaries / Q000166:cytology / Q000201:enzymology; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology*; D004847:Epithelial Cells / Q000201:enzymology; D005455:Fluorescent Antibody Technique; D006801:Humans; D008168:Lung / Q000201:enzymology*; D016676:Macrophages, Alveolar / Q000201:enzymology; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D011650:Pulmonary Alveoli / Q000166:cytology / Q000201:enzymology; D011652:Pulmonary Circulation; D012016:Reference Values; D013194:Staining and Labeling
C496320:NOS1 protein, human; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I