Effects of BH4, L-arginine (L-arg) and vitamin C (VitC) on oxidative stress in the ischemic gastrocnemius muscle. Muscle was harvested 14 d after the induction of hindlimb ischemia, and supernatants from muscle homogenates were used in these assays. (A) Nitrotyrosine expression was decreased by all dietary additives, although this decrease was greatest in rats receiving BH4 + L-arginine + vitamin C. (B) The GSH:GSSG ratio was increased in rats receiving BH4 + L-arginine; the addition of vitamin C to this regimen caused an additional increase in this ratio. Data are mean ± sd; n = 5–6. *p < 0.05 versus control, BH4 or L-arginine groups; †p < 0.05 versus BH4 + L-arginine groups.