Intake of low-dose leucine-rich essential amino acids stimulates muscle anabolism equivalently to bolus whey protein in older women at rest and after exercise

Bukhari, Syed S.I.; Phillips, Bethan E.; Wilkinson, Daniel J.; Limb, Marie C.; Rankin, Debbie; Mitchell, William K.; Kobayashi, Hisamine; Greenhaff, Paul L.; Smith, Kenneth; Atherton, Philip J.

Abstract

© 2015 American Physiological Society. All Rights Reseved. Dysregulated anabolic responses to nutrition/exercise may contribute to sarcopenia; however, these characteristics are poorly defined in female populations. We determined the effects of two feeding regimes in older women (66 ± 2.5 yr; n = 8/group): bolus whey protein (WP-20 g) or novel low-dose leucine-enriched essential amino acids (EAA) [LEAA; 3 g (40% leucine)]. Using [13C6]phenylalanine infusions, we quantified muscle (MPS) and albumin (APS) protein synthesis at baseline and in response to both feeding (FED) and feeding plus exercise (FED-EX; 6X8 knee extensions at 75% 1-repetition maximum). We also quantified plasma insulin/AA concentrations, whole leg (LBF)/muscle microvascular blood flow (MBF), and muscle anabolic signaling by phosphoimmunoblotting. Plasma insulinemia and EAA/aemia were markedly greater after WP than LEAA (P < 0.001). Neither LEAA nor WP modified LBF in response to FED or FED-EX, whereas MBF increased to a similar extent in both groups only after FED-EX (P < 0.05). In response to FED, both WP and LEAA equally stimulated MPS 0-2 h (P < 0.05), abating thereafter (0-4 h, P > 0.05). In contrast, after FED-EX, MPS increased at 0-2 h and remained elevated at 0-4 h (P < 0.05) with both WP and LEAA. No anabolic signals quantifiably increased after FED, but p70 S6K1 Thr389 increased after FED-EX (2 h, P < 0.05). APS increased similarly after WP and LEAA. Older women remain subtly responsive to nutrition ± exercise. Intriguingly though, bolus WP offers no trophic advantage over LEAA.

Citation

Bukhari, S. S., Phillips, B. E., Wilkinson, D. J., Limb, M. C., Rankin, D., Mitchell, W. K., Kobayashi, H., Greenhaff, P. L., Smith, K., & Atherton, P. J. (2015). Intake of low-dose leucine-rich essential amino acids stimulates muscle anabolism equivalently to bolus whey protein in older women at rest and after exercise. AJP - Endocrinology and Metabolism, 308(12), E1056-E1065. https://doi.org/10.1152/ajpendo.00481.2014

• Journal Article Type: Article
• Acceptance Date: Mar 26, 2015
• Online Publication Date: Mar 31, 2015
• Publication Date: Jun 15, 2015
• Deposit Date: Sep 6, 2018
• Journal: American Journal of Physiology - Endocrinology and Metabolism
• Print ISSN: 0193-1849
• Electronic ISSN: 1522-1555
• Publisher: American Physiological Society
• Peer Reviewed: Peer Reviewed
• Volume: 308
• Issue: 12
• Pages: E1056-E1065
• DOI: https://doi.org/10.1152/ajpendo.00481.2014
• Keywords: Skeletal muscle, Blood flow, Protein synthesis, Aging, Amino acids, Exercise
• Public URL: https://nottingham-repository.worktribe.com/output/1113610
• Publisher URL: https://journals.physiology.org/doi/abs/10.1152/ajpendo.00481.2014
• PMID: 25827594