Figure 7

Hydroxyproline content during oxygen exposure. The hydroxyproline content with 2 week exposure to 40% oxygen was significantly increased as compared to that with 2 week exposure to 21% oxygen. This increase was not significantly different as compared to that in the pre-exposure group. At 4, 8 and 16 week-exposure periods, there were no differences in hydroxyproline content between the 40% and the 21% exposure groups, or between the 40% and the pre-exposure groups. There were no significant differences among the 90% oxygen exposure groups. Values are expressed as means ± SD; n = 9 in the pre-exposure group; n = 5 (2 weeks), 9 (4 weeks), 5 (8 weeks) and 6 (16 weeks) in the 40% oxygen exposure groups; n = 5 (2 weeks), 8 (4 weeks), 5 (8 weeks) and 5 (16 weeks) in the 21% oxygen exposure groups; n = 5 (72 hours), 5 (96 hours) and 5 (120 hours) in the 90% oxygen exposure groups. * p < 0.05 as compared to the value of the 21% oxygen exposure duration-matched control.