Fig. 11.

Cardiac fibroblasts (CFs) were thoroughly washed with phosphate-buffered saline and incubated with N⁶-etheno-adenosine (10 μmol/L) in the absence or presence of the purine nucleoside phosphorylase inhibitor 8-aminoguanine (100 μmol/L) or forodesine (5 μmol/L). After 4 h, the medium was collected and assayed for N⁶-etheno-adenine (a, d, g) and N⁶-etheno-adenosine (b, e, h) using reverse phase high-performance liquid chromatography as described in detail in the “Analytical methods” section. The sum (N⁶-etheno-Total) of N⁶-etheno-adenine and N⁶-etheno-adenosine is shown in c, f, and i. In a, b, c, d, e, and f, cells were expanded using bovine calf serum. In g, h, and i, cells were expanded using platelet-derived growth factor rather than serum to eliminate any possibility of contaminating the cells with purine nucleoside phosphorylase from serum. Both 8-aminoguanine (a, b, c, g, h, i) and forodesine (d, e, f) abolished the formation of N⁶-etheno-adenine. Results were the same in cells expanded with versus without bovine calf serum. All individual data points are provided along with the means and SDs. *P < 0.05 versus control. ADE, adenine; ADO, adenosine; DL, detection limit