OBJECTIVETo investigate the fibrogenetic effects induced by rush-mat dust in rats.

METHODSSD rats were treated with 50 mg of rush-mat dust per rat by intra-tracheal instillation, sacrificed 3, 6, and 12 months respectively after exposure. The lung tissue and lung lymph-node were taken out for pathological and electron microscopic examination. The content of collagen and ceruloplasmin (CP) in lung tissues were also determined.

RESULTSAfter treatment for 12 months, fresh wet lung weight in rush-mat dust group [(2.69 +/- 0.22) g] was higher than those in saline group [(1.87 +/- 0.25) g], TiO(2) group [(2.25 +/- 0.26) g], but lower than that in SiO(2) group [(11.41 +/- 1.63) g]; dry lung weight in rush-mat dust group [(0.47 +/- 0.03) g] was higher than those in saline group [(0.32 +/- 0.03) g], TiO(2) group [(0.41 +/- 0.08) g], but lower than that in SiO(2) group [(2.06 +/- 0.28) g]; lung collagen content in rush-mat dust group [(103.08 +/- 14.79) mg] was higher than those in saline group [(75.96 +/- 13.91) mg, TiO(2) group [(85.84 +/- 17.62) mg], but lower than that in SiO(2) group [(497.50 +/- 100.80) mg]; CP content in rush-mat dust group [(18.03 +/- 1.87) U/L] was higher than those in saline group [(15.05 +/- 2.24) U/L], TiO(2) group [(16.92 +/- 1.67) U/L], but lower than that in SiO(2) group [(25.37 +/- 3.58) U/L], P < 0.05 or P < 0.01. Pathological examination showed lung macrophage alveolitis, broadening of alveolar interval, one to two grade of silicotic nodes and increased amount of type II epithelial cell in alveolar as well as slight collagenous fibrosis in lung tissue of rush-mat dust group. Under electron microscope, primary and secondary lysosome and medullary sheath-like phagocytic residual body were found in lung tissue of rush-mat dust group, meanwhile the amount of type II alveolar epithelial cell and collagen fiber were slightly increased but these changes were less than those of quartz group.

CONCLUSIONThe rush-mat dusts have slight pulmonary fibrogenetic effect on rat.