The protein abundance of atrogin-1 in longissimus dorsi muscle in response to age and amino acids, insulin, and leucine infusion. (A) Muscle atrogin-1 abundance from experiment 1 during euinsulinemic-euglycemic-euaminoacidemic (control; C), euinsulinemic-euglycemic-hyperaminoacidemic (AA), and hyperinsulinemic-euglycemic-euaminoacidemic (INS) clamps for 2 h in 6- and 26-d-old pigs. (B) Muscle atrogin-1 abundance from experiment 2 during euinsulinemic-euglycemic-euaminoacidemic-euleucinemic (C), euinsulinemic-euglycemic-hypoaminoacidemic-hyperleucinemic (L), and euinsulinemic-euglycemic-euaminoacidemic-hyperleucinemic (L+AA) clamps for 24 h in 5-d-old pigs. Data are normalized with β-actin abundance and are expressed in arbitrary units (AU). Values are means ± SEM, n = 4–7. Values not sharing common symbols differ significantly (P < 0.05).