Hyaluronic acid--an indicator of pulmonary injury?

Hyaluronic acid was the only glysosaminoglycan detected in the pulmonary secretions of healthy adult rats exposed to inhalation to methylene chloride, but not of control animals. The compound migrated as a single spot with the mobility of standard hyaluronic acid on cellulose acetate electrophoresis and disappeared after digestion with testicular hyaluronidase. Its identification was confirmed by finding hexuronate/hexosamine in a molar ratio of approx. 1. Glucosamine represented over 97% of the total hexosamine, the remaining 3% being galactosamine. No hexose or sulfate could be detected. Sodium dodecyl sulfate--polyacrylamide gel electrophoresis showed no protein associated with this glycosaminoglycan. It appears that the secretion of hyaluronic acid into the airways may be the result of pulmonary inflammation induced by the toxic effects of methylene chloride.