Is leucine induced p70S6 kinase phosphorylation following resistance exercise dependent on elevated phenylalanine levels in human skeletal muscle?

• The purpose of this study was to investigate the specific role ofleucine in the stimulation of the mammalian target of rapamycinsignalling pathway. Six male subjects performed four heavyresistance exercise sessions, each separated by approximately oneweek. Subjects were randomly supplemented with one of fourdrinks: placebo (flavored water), leucine or essential amino acids(EAA) with and without leucine. Immediately following eachexercise session, four subjects were infused with a flooding dose ofL-[2H5] phenylalanine (Inf) while two subjects served as controls(Ctrl). Muscle biopsies were taken before and one hour afterexercise. In the Ctrl group, resistance exercise resulted in asubstantial increase (45-fold) in p70 kinase phosphorylationwhen all EAA were ingested, whereas ingestion of leucine alonehad no greater effect than that of placebo. In the Inf group,however, ingestion of leucine alone and EAA increased p70phosphorylation to a similar extent (35-fold). The divergentsignalling response in the two groups suggests that leucine alone isinsufficient to increase p70phosphorylation. Indeed, in the Infgroup, there was a strong correlation (r=0.91) betweenp70 phosphorylation and the product of muscle leucine andphenylalanine levels. These results suggest that the stimulatoryeffect of leucine on p70 phosphorylation is dependent onelevated muscle phenylalanine levels. Supported by the SwedishNational Centre for Research in Sports 

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap -- Idrottsvetenskap (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences -- Sport and Fitness Sciences (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Physiology (hsv//eng)

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Sports

Idrott

Clinical physiology

Klinisk fysiologi

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