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dc.contributor.authorLund, Jonathan
dc.contributor.authorWilliams, John P
dc.date.accessioned2017-11-28T11:35:13Z
dc.date.available2017-11-28T11:35:13Z
dc.date.issued2017-10
dc.identifier.citationClin Nutr. 2017 Oct 6. pii: S0261-5614(17)31356-0. doi: 10.1016/j.clnu.2017.09.024.en
dc.identifier.urihttp://hdl.handle.net/20.500.12904/1294
dc.descriptionAuthor(s) Pre or Post Print Version Onlyen
dc.description.abstractBACKGROUND & AIMS: β-hydroxy-β-methylbutyrate (HMB) is purported as a key nutritional supplement for the preservation of muscle mass in health, disease and as an ergogenic aid in exercise. Of the two available forms of HMB (calcium (Ca-HMB) salt or free acid (FA-HMB)) - differences in plasma bioavailability have been reported. We previously reported that ∼3 g oral FA-HMB increased muscle protein synthesis (MPS) and reduced muscle protein breakdown (MPB). The objective of the present study was to quantify muscle protein metabolism responses to oral Ca-HMB. METHODS: Eight healthy young males received a primed constant infusion of 1,2 (13)C2 leucine and (2)H5 phenylalanine to assess MPS (by tracer incorporation in myofibrils) and MPB (via arterio-venous (A-V) dilution) at baseline and following provision of ∼3 g of Ca-HMB; muscle anabolic (MPS) and catabolic (MPB) signalling was assessed via immunoblotting. RESULTS: Ca-HMB led a significant and rapid (<60 min) peak in plasma HMB concentrations (483.6 ± 14.2 μM, p < 0.0001). This rise in plasma HMB was accompanied by increases in MPS (PA: 0.046 ± 0.004%/h, CaHMB: 0.072 ± 0.004%/h, p < 0001) and suppressions in MPB (PA: 7.6 ± 1.2 μmol Phe per leg min(-1), Ca-HMB: 5.2 ± 0.8 μmol Phe per leg min(-1), p < 0.01). Increases in the phosphorylation of mTORc1 substrates i.e. p70S6K1 and RPS6 were also observed, with no changes detected in the MPB targets measured. CONCLUSIONS: These findings support the pro-anabolic properties of HMB via mTORc1, and show that despite proposed differences in bioavailability, Ca-HMB provides a comparable stimulation to MPS and suppression of MPB, to FA-HMB, further supporting its use as a pharmaconutrient in the modulation of muscle mass.en
dc.language.isoenen
dc.subjectAnabolismen
dc.subjectProtein Metabolismen
dc.subjectSkeletal Muscleen
dc.subjectβ-Hydroxy-β-Methylbutyrateen
dc.titleImpact of the calcium form of β-hydroxy-β-methylbutyrate upon human skeletal muscle protein metabolism.en
dc.typeArticleen


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