Effect of chronic exposure to nitrogen dioxide on collagen fractions content in skin of guinea pigs.

Guinea pigs were exposed to nitrogen dioxide in concentration of 2 mg/m3 (8 hrs. daily, 180 days). Control group inspired fresh air. Collagen fractions were estimated in skin and assayed as hydroxyproline concentration. An increase of total collagen content, due to on increase of salt-soluble collagen fraction was found in the skin of the exposed animals, while a simultaneous decrease of insoluble collagen content was observed.