Leucin kan inte ensamt stimulera proteinsyntesen

[King Grub]

Mer bevis för att aminosyror som tillskott inte fungerar. Det behövs hela proteinet. Inte ens leucin duger. Det sänds signaler, men ingenting händer i praktiken.

It has been suggested that leucine is primarily responsible for the increase in muscle protein synthesis (MPS) after protein ingestion because leucine uniquely activates the mTOR‐p70S6K signaling cascade. We tested this hypothesis by measuring muscle p‐mTORSer2448, p‐p70S6KThr389, and p‐eIF2αSer51 and protein turnover (by stable isotope labeled amino acid tracer infusion in conjunction with leg arterio‐venous blood and muscle tissue sampling) in 28 women who consumed either 0.45 g protein/kg fat‐free mass (containing 0.0513 g leucine/kg fat‐free mass) or a control drink (n = 14) or 0.0513 g leucine/kg fat‐free mass or a control drink (n = 14) during a hyperinsulinemic‐euglycemic clamp procedure (HECP). Compared to basal conditions, the HECP alone (without protein or leucine ingestion) suppressed muscle protein breakdown by ∼20% and increased p‐mTORSer2448 and p‐p70S6KThr389 by > 50% (all p<0.05) but had no effect on p‐eIF2αSer51 and MPS. Both protein and leucine ingestion further increased p‐mTORSer2448 and p‐p70S6KThr389, but only protein, not leucine, ingestion decreased (by ∼35%) p‐eIF2αSer51 and increased (by ∼100%) MPS (all p<0.05). Accordingly, leg net protein balance changed from negative (loss) during basal conditions to equilibrium during the HECP alone and the HECP with concomitant leucine ingestion and to positive (gain) during the HECP with concomitant protein ingestion. These results provide new insights into the regulation of MPS by demonstrating that leucine and mTOR signaling alone are not responsible for the muscle anabolic effect of protein ingestion during physiologic hyperinsulinemia, most likely because they fail to signal to eIF2α to initiate translation and/or additional amino acids are needed to sustain translation.

The muscle anabolic effect of protein ingestion during a hyperinsulinemic euglycemic clamp in middle‐aged women is not caused by leucine alone. The Journal of Physiology, 27 July 2018 .

https://physoc.onlinelibrary.wiley.c....1113/JP276504

[ChuckTesta]

Varför tycks EAA fungera vid sängliggande?

[King Grub]

Fast i dom studierna har alla aminosyror som kroppen inte själv kan syntetisera tillförts.