Figure 1. Primary rat articular chondrocytes were isolated and grown in monolayer cultures for 48 h with or without rAC (rAC, 200 U/ml) added to the media.

At the indicated times proteins and lipids were extracted from the cells, and A) AC activity, B) ceramide, C) sphingosine, and D) sphingosine-1-phosphate levels were determined. Note that the addition of rAC to the culture media (gray bars) led to markedly increased AC activity in the cells by 12 h that was sustained for at least 48 h. In addition, by 12 h ceramide levels were elevated compared to baseline, but significantly less so in cells treated with rAC (i.e., by 48 h cells treated with rAC had no detectable ceramide elevation). Finally, the levels of S1P and sphingosine were elevated in rAC-treated cells by 12 and 48 h, respectively. * = p<0.05.