Release of hydrogen peroxide by rat type II pneumocytes in the prolonged culture

• Published in: Toxicology in vitro 2000-02, Vol.14 (1), p.85-93
• Main Authors: Piotrowski, W.J, Marczak, J, Dinsdale, D, Kurmanowska, Z, Tarasow, Y, Komos, J, Nowak, D
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Catalase - metabolism; Cell Count; cell culture; Cell metabolism, cell oxidation; Cell physiology; Cell Separation; Cells, Cultured; Fundamental and applied biological sciences. Psychology; hydrogen peroxide; Hydrogen Peroxide - metabolism; Lung - cytology; Lung - metabolism; Lung - ultrastructure; Male; Microscopy, Electron; Molecular and cellular biology; pneumocytes; Potassium Cyanide - pharmacology; Protein Kinase C - metabolism; Rats; Rats, Wistar; Tetradecanoylphorbol Acetate - pharmacology; type II pneumocyte
• ISSN: 0887-2333; 1879-3177
• DOI: 10.1016/S0887-2333(99)00080-6

Type II pneumocytes (T II pneumocytes) produce hydrogen peroxide (H 2O 2), which may be potentially dangerous for the lung. These cells in culture differentiate to type I-like pneumocytes and it may reflect the differentiation which follows the injury of alveolar epithelium. This work was undertaken to estimate the H 2O 2 release by T II pneumocytes, freshly isolated and cultured up to 8 days. The light and electron microscopy evaluation confirmed the differentiation of T II pneumocytes to type I-like cells. The release of H 2O 2, estimated spectrofluorimetrically as homovanillic acid oxidation product obtained in the presence of horseradish peroxidase, was significantly higher at day 4 (0.63±0.68 nmol/mg protein/min, P⩽0.02) and 6 (0.46±0.31, P⩽0.001) compared to fresh cells (0.15±0.08). Phorbol esters increased H 2O 2 release at day 2 (0.39±0.22 vs 0.16±0.08, P⩽0.02) and the inhibition of protein kinase C resulted in the decrease at day 2 (0.14±0.06 vs 0.07±0.02, P⩽0.025), day 6, (0.49±0.25 vs 0.15±0.08, P⩽0.005) and 8 (0.76±0.63 vs 0.23±0.29, P⩽0.02). Inhibition of intracellular catalase resulted in a significant increase only at day 2 (0.23±0.1 vs 0.15±0.09, P⩽0.05). Inhibition of mitochondrial respiratory chain decreased H 2O 2 release at day 2 (0.13±0.11 vs 0.07±0.07, P⩽0.002) and 4 (0.75±0.88 vs 0.61±0.85, P⩽0.002). These results indicate that alveolar epithelium may be a source of potentially dangerous ROS and that the cell differentiation is accompanied by the increase of H 2O 2 production. Both mitochondrial respiratory chain and membrane-bound NADPH-oxidase may be responsible for the production of H 2O 2 by T II pneumocytes.