Effect of acute and chronic paraquat on rat lung collagen content.

The effect of acute and chronic paraquat administration on rat lung collagen was studied. A single dose of paraquat (35 mg/kg, ip) produces a transient increase in lung collagen synthesis within the first several days. In animals sacrificed 18 days later, there is insignificant accumulation of collagen (9%). Three injections of paraquat (25 mg/kg) spaced at weekly intervals produces a 31% increase in lung collagen by the middle of the fourth week. In view of the technical difficulties involved with the use of paraquat as a pulmonary fibrotic agent in the rat, search for an alternative model is suggested.