Collagen metabolism following corneal laceration in rabbits.

We investigated the synthesis and degradation of collagen in lacerated rabbit corneas. The rate of collagen synthesis was measured by the incorporation and hydroxylation of [14C]proline up to 5 weeks after a penetrating laceration. Our results indicate that protein and collagen synthesis is initially reduced during the 24 h period after laceration and then increases in two phases. A moderate increase in protein and collagen synthesis occurs up to day 5 after laceration. Synthesis then decreases to a low level through the 10th day after injury. A second wave of increase in protein and collagen synthesis takes place reaching a new peak of approximately twice the activity as found in control corneas after 5 weeks of healing. Afterwards, the rate of protein and collagen synthesis declines and reaches the basal level after 7 weeks of healing. In a separate set of experiments, rabbit corneas were lacerated and allowed to heal for one or three weeks at which point 100 microCi of [14C]proline was injected into each anterior chamber. The corneas were excised 1 to 17 days later and subjected to collagen analysis. Our data indicates that the degradation of collagen synthesized by the cornea 1 week after laceration followed biphasic kinetics. In the first phase, the half-life of newly-synthesized collagen is 20 days, whereas it is approximately 4 days in the second phase. It is of particular interest that the accelerated degradation of the newly-synthesized [14C]collagen is concomitant with the increased rate of collagen synthesis during the wound healing process. The degradation of collagen synthesized 3 weeks after injury was slower and followed monophasic kinetics having a half-life of 14 days. The degradation of non-collagenous 14C-proteins follow a monophasic kinetics having a half-life of 6-7 days. Polyacrylamide gel electrophoresis of newly-synthesized collagen indicated that the collagen(I) and collagen(V) were the main collagenous components synthesized by the lacerated corneas.