Changes in the red cell eNOS expression and activity in patients with endothelial dysfunction. (A) Monovariate linear correlation analysis between red cell eNOS expression as evaluated by Western blot analysis and endothelium-dependent flow mediated dilation (FMD) in patients affected with endothelial dysfunction and healthy individuals (healthy). (B) The activity of red cell eNOS was evaluated in a randomized subset of the groups by evaluating the conversion of ¹⁴C-L-arg into ¹⁴C-L-citrulline. Total radioactivity is expressed as counts per minute (cpm); t test *P = .0359.