The effects of intratracheally-administered imipramine on the rat lung.

The tricyclic antidepressant imipramine was instilled directly onto the lung surface of experimental rats in specific low doses (0.025 - 0.60 mg/kg body weight) and the animals were sacrificed at time intervals from 2 - 21 days after a single instillation. Such treatment caused changes almost exclusively confined to the alveolar surface. Alterations were induced in the free cell numbers and lung lavage protein levels while alveolar lipid and pulmonary surfactant levels were elevated. All such changes could be considered indicative of a mild toxic reaction. Imipramine at these low dose levels appeared specific in its effect in promoting surfactant accumulation in the absence of other toxic effects.