Oxidative stress contributes to the age related decline in basal leg blood flow in sedentary men

Older men have reduced basal leg blood flow compared with young men, but the underlying mechanisms are incompletely understood. We determined if oxidative stress, which develops with aging and can exert a vasoconstrictor influence, plays a role. Common femoral artery blood flow was measured (duplex ultrasonography) under 3 conditions in young (n = 7; 24 ± 1 yrs) and older (n = 9; 64 ± 2 yrs) sedentary men who did not differ in leg fat free mass: acute intravenous infusion of saline or a supraphysiological concentration of ascorbic acid, and after 30 days of oral ascorbic acid supplementation (500 mg/day). At baseline (saline), older men demonstrated reduced leg blood flow (210 ± 16 vs. 288 ± 25 ml/min, P < 0.05) and greater systemic oxidative stress (plasma oxidized LDL 77 ± 8 vs. 53 ± 4 IU/l, P < 0.05) compared with young men. Acute infusion of ascorbic acid restored leg blood flow in older men (277 ± 25 ml/min, P < 0.05) without affecting blood pressure, but did not influence blood flow in young men (299 ± 47 ml/min). Chronic oral ascorbic acid supplementation did not affect femoral blood flow in either group. These results provide evidence that oxidative stress mediates the age related reduction in basal leg blood flow in healthy sedentary men. However, oral supplementation of ascorbic acid does not improve leg blood flow in older men, possibly because circulating concentrations are inadequate to exert a potent antioxidant effect.