Electron-microscopic evidence for cytochrome P-450 in Clara cells and type I pneumocytes of the rat lung.
Using immunoelectron microscopy, we examined the distribution of cytochrome P-450 in rat lungs and determined the cell types in which P-450 was localized. To demonstrate P-450, a rabbit polyclonal antibody against P-450b (P-450 IIB1), the major constitutive isozyme of rat pulmonary P-450, was used. Strong reactivity for anti-P-450b antibody was observed in nonciliated bronchial and bronchiolar epithelial cells (Clara cells) and type I pneumocytes. Type II pneumocytes and Kultschitzky cells showed no reactivity. Most ciliated cells were negative, although a small number in peripheral bronchioles showed a weakly positive reaction. Endothelial cells and other mesenchymal cells were P-450b negative. Many studies have suggested that the Clara cell was metabolically very active and had P-450 containing mixed function oxidase systems. Our study shows that both Clara cells and type I pneumocytes have P-450 and may play an important role in the metabolism of xenobiotics. The metabolic significance of type I pneumocytes was not recognized, but it is reasonable to postulate that type I pneumocytes may have a xenobiotic metabolic function because they comprise most of the surface area of the lungs and are thus extensively exposed to the environment.
Aida
S
S
Department of Laboratory Medicine, National Defense Medical College, Tokorozawa, Japan.
Takahashi
Y
Y
Suzuki
E
E
Kimula
Y
Y
Ito
Y
Y
Miura
T
T
D000818:Animals; D001980:Bronchi / Q000378:metabolism / Q000648:ultrastructure; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism / Q000648:ultrastructure; D007150:Immunohistochemistry; D008168:Lung / Q000378:metabolism* / Q000648:ultrastructure*; D008297:Male; D016253:Microscopy, Immunoelectron; D051381:Rats; D017208:Rats, Wistar; D015262:Xenobiotics / Q000378:metabolism
D015262:Xenobiotics; D003577:Cytochrome P-450 Enzyme System