Comparing the effects of ARG co-incubation with various agents on eNOS function and oxidative stress. HUVEC were incubated with either 100 μM ARG for 2 h in buffer (short-term or acute exposure), or for 7 days in culture medium and challenged for 2 h in buffer (continuous or chronic exposure), in the presence or absence of other agents. Total NO2–/NO3– assay measurement (A) shows the importance in maintaining eNOS and AMPK activity with cellular NO production. The inhibition of AMPK or eNOS function, increased cellular O2•– (B) and ONOO– (C), that were maintained close to control conditions when cellular glucose synthesizing pathway was disrupted. n = 6. *, represents significant variation between control and treatment groups at p < 0.05. §, represents variation in treatment groups from cells treated with 100 μM ARG, at p < 0.05.