Time course of the effect of NE on SLPI concentration. Figure 5a: PBEC were cultured in basal media for 24 h, and then an aliquot of media was removed as baseline and replaced with the same volume of media control or media containing NE at a concentration sufficient to achieve a concentration of 10 nM in the wells. Further aliquots were taken at the times shown, and SLPI concentration was measured by ELISA. The figure shows the results from 3 experiments. The y axis gives the concentration of SLPI as % of the baseline value for triplicate wells treated with basal media or NE. (Error bars indicate SEM.) The concentration of SLPI fell at the earliest time point studied in wells treated with NE but remained stable in the media controls. Over 24 h the concentration in media controls rose in accordance with the steady state concentrations predicted, but remained low in NE-treated wells. At 24 h, some SLPI was present in the media of NE-treated cells but this was substantially lower than the media controls (p < 0.001 Wilcoxon signed ranks test). b: HepG2 cells were cultured in 12 well plates and, after rinsing with PBS, media containing 1 nM SLPI was added to the cells. After a few minutes equilibration, a baseline aliquot was removed and replaced with either media control or NE to achieve a final concentration of 10 nM. Further aliquots were taken at the time points shown. In the media controls it remained stable throughout, but the concentration in NE-treated wells fell significantly at 10 minutes and remained low thereafter (p < 0.001 Wilcoxon signed ranks test).