Figure 6

Type III collagenolytic enzyme activity. Type III collagenolytic enzyme activity in the 40% oxygen 2 week-exposure group was significantly increased as compared to that in the 21% oxygen 2 week-exposure group. This increase was, however, 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 type III collagenolytic enzyme activity between the 40% and the 21% exposure groups, or between the 40% and the pre-exposure groups. Type III collagenolytic activities in the 40% oxygen 8 week-exposure groups was decreased as compared to that in the 40% oxygen 2 week-exposure group. There was no significant difference among the 90% oxygen exposure groups. Values are expressed as means ± SD; n = 8 in the pre-exposure group; n = 7 (2 weeks), 10 (4 weeks), 6 (8 weeks) and 6 (16 weeks) in the 40% oxygen exposure groups; n = 5 (2 weeks), 8 (4 weeks), 5 (8 weeks) and 6 (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. ++ p < 0.01 as compared to the value of the 40% oxygen 2 week-exposure group.