Effects of intratracheal instillation of dactinomycin on pulmonary edema and phosphatase activity of the lung lavage fluid in rats.

Intratracheal (i.t.) administration of protein synthesis inhibitors produced pulmonary edema. Of those inhibitors studied, dactinomycin (act. D) was the most potent. Severity of lung damage due to act. D was dose- and almost age-related. Maximal intensity of pulmonary edema was reached on the 3rd day following administration and remained constant for 14 days. Histopathological studies revealed confluent edema of the entire lung. Pretreatment with act D induced tolerance to an LD100 edematogenic dose of thiourea. The effects of i.t. instillation of act. D appear to be localized in the pulmonary tissue. Lung lavage fluid collected from drug-treated rats had higher acid and alkaline phosphatase activities, higher protein content and more leukocyte infiltration than that of control.