Assessment of glucose-stressed EPC cultures. (a) Number of colonies (CFUs) of non-stressed EPCs (normal glucose (5 mmol/L) (NG)), glucose-stressed EPCs (25 mmol/L D-glucose (HG)), and an osmolarity control (25 mmol/L L-glucose (LG)). (b) Superoxide anion (O2-) generation in non-stressed and glucose-stressed EPCs in the absence or presence of apocynin. (c) SOD activity in non-stressed EPCs (NG), glucose-stressed EPCs (HG), glucose-stressed EPCs treated with apocynin, and an osmolarity control (25 mmol/L L-glucose (LG)). (d) NO levels in non-stressed EPCs (NG), glucose-stressed EPCs (HG), glucose-stressed EPCs after being treated with apocynin, an inhibitor of NAD(P)H oxidase, and glucose-stressed EPCs after being treated with L-NAME, a non-specific inhibitor of NOS. Data are expressed as mean percentage ± SEM or mean number ± SEM of triplicate measurements in each sample from four independent tests. *P < 0.05, **P < 0.01, ***P < 0.001 vs. non-stressed EPCs (control). NS represents non-significant.