Λευκίνη και HMB - Επίδραση Στον Μυικό Αναβολισμό
Αν και δεν εχω διαβασει ολο το κειμενο, αυτη η ερευνα δειχνει καποια πολυ θετικα στοιχεια σχετικα με τη λευκινη και τα συμπληρωματα hmb, και τη θετικη τους επιδραση στην πρωτεινοσυνθεση και τη μειωση του καταβολισμου.
Effects of Leucine and its metabolite, β-hydroxy-β-methylbutyrate (HMB) on human skeletal muscle protein metabolism
Daniel J Wilkinson1,5,
Tanvir Hossain1,
Derek S Hill1,
Bethan E Phillips1,
Hannah Crossland1,
John Williams1,
Paul Loughna1,
Tyler A Churchward-Venne2,
Leigh Breen2,
Stuart M Phillips2,
Timothy Etheridge3,
John A Rathmacher4,
Kenneth Smith1,
Nathaniel J Szewczyk1 and
Philip J Atherton1
- Author Affiliations
1 University of Nottingham, UK;
2 McMaster University, Canada;
3 Bournemouth University, UK;
4 Metabolic Technologies Inc., US
Abstract
Maintenance of skeletal muscle mass is contingent upon the dynamic equilibrium (fasted losses-fed gains) in protein turnover. Of all nutrients, the single amino acid Leucine (Leu) possesses the most marked anabolic characteristics in acting as a trigger element for the initiation of protein synthesis. While the mechanisms by which Leu is "sensed" have been the subject of great scrutiny, as a branched-chain amino acid, Leu can be catabolized within muscle, thus posing the possibility that metabolites of Leu could be involved in mediating the anabolic effect(s) of Leu. Our objective was to measure muscle protein anabolism in response to Leu and its metabolite HMB. Using [1,2-13C2]Leu and [2H5]phenylalanine tracers, and GC-MS/GC-C-IRMS we studied the effect of HMB or Leu alone on MPS (by tracer incorporation into myofibrils), and for HMB we also measured muscle proteolysis (by A-V dilution). Orally consumed 3.42g free-acid (FA-HMB) HMB (providing 2.42g of pure HMB) exhibited rapid bioavailability in plasma and muscle and, similarly to 3.42g Leu, stimulated MPS (HMB: +70% vs. Leu: +110 %). While HMB and Leu both increased anabolic signaling (mechanistic target of rapamycin; mTOR), this was more pronounced with Leu (i.e., p70S6K1 signaling ?90 min vs. ?30 min for HMB). HMB consumption also attenuated MPB (-57 %) in an insulin-independent manner. We conclude that exogenous HMB induces acute muscle anabolism (increased MPS and reduced MPB) albeit perhaps via distinct, and/or additional mechanism(s) to Leu.
