Fig. 6.

Effect of hyperosmolarity on total levels and stability of COL2A1 mRNA in freshly isolated HAC. A: real-time PCR analysis of COL2A1 mRNA levels in freshly isolated HAC cultured at 380 or 550 mosM for 5 or 24 h. Each donor's samples were measured twice, and for each donor and each condition, all data were normalized to the first 380 mosM value recorded (*P < 0.05, n = 3; **P < 0.01, n = 4). B: real-time PCR analysis of COL2A1 mRNA decay. Freshly isolated chondrocytes were cultured at 380 or 550 mosM for 2 h before addition of actinomycin D. RNA was then extracted in triplicate at 0, 1, 2, and 3 h for reverse transcription and analyzed by real-time PCR. Data represent means and SDs of the fold changes in COL2A1 mRNA levels compared with time point 0 (n = 4).