Pulmonary interstitial fibrosis from paraquat in the hamster

The effects of paraquat in hamsters were evaluated to find a rodent model of interstitial pulmonary disease free from spontaneous infection. Because the repeated doses necessary to produce chronic lung injury suggested hypersensitivity mechanisms, concurrently administered Freund adjuvant and adenocorticotrophic hormone (ACTH) were tested separately. Effects were measured by mortality, change in body weight, and morphometric estimate of lung injury. Findings were as follows: (1) only repeated doses in a very narrow range produced chronic interstitial injury; (2) ACTH clearly protected animals from the general systemic and pulmonary effects of paraquat; and (3) adjuvant specifically protected against the pulmonary injury alone. There was no evidence of immunologic contribution to paraquat injury.