Pulmonary uptake of mannitol as an index of changes in lung epithelial permeability

To develop a simple, inexpensive, and nontoxic test for changes in bronchial permeability we have employed a specific gas chromatographic assay to measure the uptake of mannitol from the lung after administration of an intratracheal aqueous bolus (8 ml of 5% solution). We have tested the ability of our method to detect the known increase in lung epithelial permeability elicited by challenge of previously sensitized animals with aerosols of Ascaris suum antigen. In Ascaris-sensitive Basenji-Greyhound dogs, antigen challenge significantly increased the rate of appearance and peak plasma level of mannitol after administration of the intratracheal bolus. Peak plasma mannitol levels averaged 25 +/- 3 (SE) micrograms/ml in dogs challenged with Ascaris antigen aerosols, and 14 +/- 2 micrograms/ml in the same animals in separate control experiments employing saline aerosols. The method presented could be readily applied to animal and human studies as a simple, inexpensive, and nontoxic indicator of lung epithelial permeability.