Effects of BH4, L-arginine (L-arg) and vitamin C (VitC) on eNOS and phosphorylated eNOS expression 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) Expression of eNOS was increased by all dietary additives, although the greatest increase was noted in rats that received BH4 + L-arginine + vitamin C. (B) Expression of p-eNOS was increased in rats fed BH4 + L-arginine or BH4 + L-arginine + vitamin C. Control rats were fed a standard diet, whereas the four treatment groups consumed diets supplemented with additives noted in the bar graph. Concentrations of these additives are noted in the text. Data are mean ± standard deviation (sd); n = 5–6. *p < 0.05 versus control; p < 0.05 versus BH4 or L-arginine groups; ‡p < 0.05 versus BH4 + L-arginine group.