Figure 4.

(R)-α-lipoic acid (LA) and glutathione monoethylester (GE) partially restored the age-associated inactivation of endothelial nitric oxide synthase (eNOS) and Akt in the aortic endothelium. Endothelial plasma membrane fractions were prepared from young and old rats, or old rats treated with either LA, GE or saline. The phosphorylation status of eNOS (S1176) and Akt (S473) was analysed by western blot. (a) LA significantly improved the age-related decline in both Akt and eNOS phosphorylation. (b) Digital quantification of western blots reveals that Akt phosphorylation (S473) declines by 52% with age, which is significantly restored by LA administration. (c) Age leads to a 46% decline in eNOS phosphorylation, which is almost completely restored by LA. (d) GE increases endothelial Akt and eNOS phosphorylation in aortas from old rats. (e) Digital quantification of the blots illustrates that GE causes a 55% increase in Akt phosphorylation over untreated or saline-treated old animals. (f) Similar improvements in eNOS phosphorylation are also observed by GE administration to old animals. GE treatment led to an 80% increase in eNOS phosphorylation in old animals compared with either untreated or saline-treated animals. (n=4) ^*Statistical significance compared with young controls (P⩽0.01). ^†Statistical significance compared with old controls (P⩽0.02).