Alteration of collagen synthesis in lung organ cultures by hyperoxic environments

Organ cultures of neo-natal rat lungs continue to accumulate collagen at a nearly linear rate for 5 days, when maintained in an atmosphere consisting of 5% CO₂ in air. Nearly 70% of the collagen synthesized in these cultures is Type I and 30%, Type III. When these cultures are maintained in 5% CO₂ + 95% O₂, the per cell accumulation of collagen increased. Although there is no significant change in the amount of radiolabeled proline incorporated, the rate of incorporation per cell is increased since there appear to be fewer cells in the O₂-treated cultures. These parameters of collagen synthesis parallel lung O₂ injury in vivo. There is a shift in the type of collagen synthesized, nearly 70% being Type III and 30%, Type I in O₂-exposed cultures. This finding is reminiscent of tissue repair after injury. Such changes in collagen may contribute to pulmonary connective tissue disorders in oxidant-induced lung injury.