Kinetics of inhaled lipopolysaccharide in the guinea pig.

The kinetics of endotoxin in the airway and the blood was studied after an inhalation exposure using guinea pigs. The amounts of endotoxin in the pulmonary lavage fluid, and in arterial and venous blood were determined. Forty minutes after the start of exposure to 400 micrograms/m3 of Escherichia coli 026:B6-LPS, 7.7 +/- 2.9 ng/ml of lipopolysaccharide (LPS) could be demonstrated in the pulmonary lavage fluid, and 60 minutes afterwards, the amount was 4.9 +/- 1.4 ng/ml. In the arterial blood, the amounts at 10 and 40 minutes of exposure, and 60 minutes afterwards were 21.2 +/- 23.8 pg/ml, 29.2 +/- 31.8 pg/ml, and 1.1 +/- 1.0 pg/ml, respectively. There was no significant difference of LPS content in the arterial and venous blood. The results demonstrate that the lung is a potent barrier for penetration of endotoxins into the body. The experimental model enables studies of how other exposures such as mineral dusts, tobacco smoke, or viral or bacterial infections might affect this defense.