Early phase collagen synthesis in lungs of rats exposed to bleomycin.
Skin wound healing exhibits type III collagen synthesis occurring transiently as early as 10 h after injury, with subsequent synthesis of type I to form a scar. We hypothesized that similar collagen type switching also occurred in the bleomycin model of lung fibrosis in the rat. We could measure elevated lung collagen synthesis rates as early as 4 days after administration of bleomycin. Collagen type I:III ratios in whole lung remained constant for the first 7 days at the control level of 2:1, then increased to as high as 5:1 at day 21. Procollagen mRNA content, expressed as a ratio of type I:III mRNAs, was consistent with the protein synthesis data and the observed ratio of collagen types being made by the lungs at the various time points evaluated. We conclude that a transient increase in type III relative to type I collagen does not occur in the bleomycin rat lung model. Therefore, the sequence of type-specific collagen expression and deposition in the skin wound healing model is not entirely analogous to this widely used animal model of pulmonary fibrosis.
Van Hoozen
B E
BE
Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of California, Davis, CA 95616-8723, USA.
Grimmer
K L
KL
Marelich
G P
GP
Armstrong
L C
LC
Last
J A
JA
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D001761:Bleomycin / Q000633:toxicity*; D015152:Blotting, Northern; D003094:Collagen / Q000096:biosynthesis*; D007700:Kinetics; D008168:Lung / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D011347:Procollagen / Q000096:biosynthesis; D011658:Pulmonary Fibrosis / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012822:Silicon Dioxide / Q000633:toxicity
D000903:Antibiotics, Antineoplastic; D011347:Procollagen; D012333:RNA, Messenger; D001761:Bleomycin; D012822:Silicon Dioxide; D003094:Collagen