[Nitric oxide synthase in lung epithelial cells in culture]

To identify the molecular nature of nitric oxide synthase (NOS) and its regulation and function in the airway, NOS activity and NOS mRNA expression were measured in cultured lung epithelial cell. All epithelial cells exhibited constitutive NOS activity that was calcium-dependent, and inducible, lesser calcium-dependent activity in the presence of interferon-gamma, interleukin-1 beta, tumor necrosis factor-alpha, and lipopolysaccharide. Two distinct NOS mRNA species (neuronal and inducible) were found with the reverse transcription polymerase chain reaction. The co-existence of constitutive and inducible NOS in human alveolar and bronchial epithelial cells indicates that nitric oxide may have many roles in normal and diseased lungs.