Figure 4.

Superoxide production in aortic rings from control rats and diabetic rats (STZ) treated either with placebo or sildenafil (5 mg kg⁻¹ day⁻¹ for 2 weeks) was detected and quantified by lucigenin-enhanced chemiluminescence (a). Expression of the NADPH oxidase subunit gp91^phox (b) and membrane expression of the small G protein Rac-1, a NADPH oxidase regulator (c), were assessed by western blot. Mean±s.e.mean from 6 to 10 separate experiments. ^*P<0.05 vs Control; ^#P<0.05, ^##P<0.01 vs STZ-placebo. Confocal microscopy of 10-μm-thick aortic sections incubated with the fluorescent dye hydroethidium to visualize superoxide formation throughout the vascular wall (d). NADPH, nicotinamide adenine dinucleotide phosphate; STZ, streptozotocin.