Cyclophosphamide-induced generation of reactive oxygen species. Comparison with morphological changes in type II alveolar epithelial cells and lung capillaries.

Cyclophosphamide (CP) causes lung toxicity in animals and humans. The mechanisms of pulmonary damage caused by CP are not fully understood. Possibilities include direct toxicity to pulmonary tissue or indirect toxicity through activation of pulmonary inflammatory cells. The aim of the present study was the ultrastructural analysis (in transmission electron microscope) of the changes following CP administration within the structures forming the interalveolar septum of the lungs, particularly type II epithelial cells. An attempt was also made to reveal a correlation between the morphological changes, intensity of lipid peroxidation in lung tissue homogenates and blood serum collected from the left ventricle of the heart and the alterations in the activities of superoxide dismutase (Cu, Zn-SOD) and glutathione reductase (GSSG-R). The experiment used 40 male Wistar rats of 160-180 g body weight (b.w.). The animals were divided into two groups. Group I - (20 animals) were given single intraperitoneal (i.p.) dose of 150 mg CP/1 kg b.w./1 ml PBS. Group II - (20 animals) were given single i.p. dose of 1 ml PBS. All experimental animals were sacrificed after 1 (subgroups I, II-1) and 7 (subgroups I, II-7) days of CP (or PBS) treatment. I.p. administration of CP caused an increase in lipid peroxidation products (MDA-malondialdehyde) in lung tissue homogenates especially in subgroup I-1 (p = 0.00174). No statistical differences, however, were noted in the blood serum MDA levels, although a statistically significant decrease was found in GSSG-R (p = 0.00174) and SOD (p = 0.00174) activities in the serum. The paper discusses a potential link between the findings of biochemical analysis and the morphological changes found within lung tissue. Pulmonary trombopoesis was indicated as a possible mechanism preventing a decrease in blood platelet count following CP administration.