The Effect of Colchicine on the Accumulation of Hydroxyproline and on Lung Compliance after Irradiation

The development of late radiation fibrosis in rat lung after a single dose of 750, 1000, 1250, or 1500 rad of γ radiation was studied. The concentration of hydroxyproline was measured to evaluate collagen deposition in irradiated and control lungs. At 120 days after irradiation a linear dose-response curve can be established. Colchicine, known to modify collagen secretion and deposition, was used to modify lung fibrosis after irradiation. It was found that collagen deposition can be reduced only if colchicine is injected when the lung collagen is being synthesized, namely around 90 days after irradiation with these doses. Lung compliance at intervals up to 150 days after irradiation is reduced mainly as a result of increase in lung weight, not collagen deposition.