Ornithine decarboxylase: a biochemical marker of repair in damaged tissue

The purpose of this study was to: (a) determine the temporal pattern of expression of ornithine decarboxylase (ODC), an established marker of cells engaged in proliferation and differentiation, during repair of traumatized skeletal muscle, and (b) evaluate ODC as a biochemical marker for indexing the extent and rate of repair of traumatized skeletal muscle in response to therapeutic agents. Adult female Wistar rats weighing 240 to 280 grams were anesthetized and injected with 100 ul of 2% lidocaine into the right or left anterior tibialis muscle to induce a localized injury. The animals were treated 1 hour post-injection and every 12 hours for five minutes up to the time of sacrifice using ultrasonic irradiation at 1.5 watts/cm2, sham-irradiation, or no treatment. An analysis of variance for repeated measures and a Tukey's post hoc test were used to determine the significance of treatment effects. Animals irradiated with ultrasound demonstrated an accelerated pattern of change in ODC activity at 24 hours (P less than 0.001), 30 hours (P less than 0.003), and at 48 hours (P less than 0.002) compared to control and sham-irradiated animals at these time intervals. Irradiated animals also demonstrated less edema at 48 hours compared to sham-irradiated and control animals (P less than 0.003). These findings suggest that ODC is a useful biochemical marker for determining the extent and rate of tissue repair in traumatized skeletal muscle, and it provides a temporal and quantifiable parameter for evaluating the efficacy of therapeutic agents used to treat damaged skeletal muscle.