Figure 6.

Compression increases cyclooxygenase type 2 (COX-2) gene expression but not COX-1 nor COX-3 in mouse costal cartilage explants. (a-c) Real-time RT-PCR assays demonstrating increased COX-2 gene expression after 2 h and 4 h in compressed explants versus control and no increase for COX-1 and COX-3. Standard curves for COX-1, COX-2, COX-3 and hypoxanthine-guanine phosphoribosyltransferase (HPRT) were generated by serial dilution of a cDNA mixture. The amount of COX-1, COX-2 and COX-3 mRNA was normalized against the amount of HPRT mRNA measured in the same cDNA. Values are the mean ± SEM of 4 independent experiments with n = 1/group/experiment for COX-1 and COX-2 and of 2 independent experiments with n = 1/group/experiment for COX-3. *p < 0.05, **p < 0.01 versus control (NC). (d) Explant lysates were analyzed by SDS-PAGE using 8% gradient gels. Proteins were transferred to a nylon membrane and successively blotted with anti-COX-1, anti-COX-2, anti-COX-3 and anti-β-actin antibodies. An increased expression of COX-2 protein in compressed cartilage compared to uncompressed, but not COX-1 and COX-3, was observed after 4 hours of compression up to 24 hours. Each blot is representative of three independent experiments.