Meal with both fast and slow protein maintains high level of plasma amino acids compared to a meal with slow protein alone in rats

• Published in: The FASEB journal 2008-04, Vol.22 (S2), p.690-690
• Main Authors: Hirota, Ayumi, Yaji, Keiko, Okada, Sachiko, Kondo, Emi, Inoue, Nagisa, Tai, Sinji, Okamura, Koji
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.22.2_supplement.690

Increasing plasma amino acid concentration is one of the factors to stimulate skeletal muscle protein synthesis. In addition, maintaining plasma amino acid at a high concentration appears to be another factor to enhance muscle protein synthesis. To investigate whether a combination of protein sources with fast and slow absorption rate would benefit to achieve high plasma amino acid concentration for a longer period of time, 11 male SD rats, 5 weeks old, consumed a meal containing both casein (slow protein) and whey (fast protein) (SF, n = 6) or a meal containing casein alone (S, n = 5) after a overnight fast. Both meals contained sucrose and the ratio of protein:sucrose was 6:4. The ratio of casein and whey of the SF meal was 1:1. The rats of SF and S consumed 3.13 g (SD 0.72) and 2.30 g (0.47) of respective meal within 15 min, respectively. Plasma samples were obtained before and 15, 30, 60, 90, 120 min after the meal. The peak level of plasma total amino acids was observed 30 min after the meal in the both groups without difference between SF and S (6265 and 6162 nmol/L). The plasma total amino acid concentration remained high in SF until 120 min, while it decreased in S. As a result, it was higher in SF than S (6128 vs 4882 nmol/L) at 120 min. The plasma concentration of essential amino acids, non‐essential amino acids and branched‐chain amino acids showed similar results. These results suggest that a mixture of slow and fast protein could maintain a higher plasma amino acid concentration for longer duration compared to slow protein alone.