Collagen and prolyl hydroxylase levels in lungs of beagles exposed to air pollutants

Beagles were exposed to raw and photochemically reacted auto exhaust, oxides of nitrogen and sulfur, alone and in combination, for over five years after which they were placed in atmospheric air for 2 1 2 to 3 years. After sacrifice, the collagen content and prolyl hydroxylase levels of portions of the left lungs were determined. The latter was used as an estimate of the ability of the lungs to synthesize collagen. No significant difference was seen in the collagen concentration of the lungs in the nonexposed vs the exposed animals. There was a pronounced difference in prolyl hydroxylase levels between control lungs and lungs exposed to irradiated exhaust, high oxides of nitrogen, and irradiated exhaust plus oxides of sulfur. Exposure to low oxides of nitrogen and to oxides of sulfur, alone and in combination with and to nonirradiated exhaust, produced smaller differences in the enzyme level.