Figure 4From: The progressive ankylosis gene product ANK regulates extracellular ATP levels in primary articular chondrocytesRole of P2X7 receptors in signaling and eATP efflux by chondrocytes. (A) Chondrocytes were treated with no additives (control) or P2X7 inhibitors (Brilliant Blue G (BBG), AZ10606120 or A438079) for 1 h in the presence of 1 mM ATP. Prostaglandin E2 (PGE2) levels in the media were measured using the Parameter™ Prostaglandin E2 kit (R&D Systems). Bars represent mean ± standard error. BBG reduced ATP-induced PGE2 levels (n = 8; ***P <0.001). (B) Chondrocytes were transfected with siRNA for P2X7 or a scrambled control. After 48 h, cells were exposed to hypotonic media for 10 minutes (gray bars) or isotonic media (black bars) and eATP levels were measured. Bars represent mean ± standard error. Under control conditions, a hypotonic challenge consistently increases (eATP). No differences in eATP levels were noted in siP2X7-treated chondrocyte media (n = 8; P >0.05). In parallel cultures at 48 h, protein and mRNA were isolated from scramble or siRNA-treated cells as described and used to assess levels of P2X7 receptor protein (C) and mRNA (D). mRNA levels of P2X7 were suppressed in siRNA-treated cells (*P <0.05). Western blots compare the effects of siRNA effects on P2X7 receptor levels versus actin.Back to article page