PMID- 15304378
OWN - NLM
STAT- MEDLINE
DCOM- 20041216
LR  - 20211203
IS  - 0193-1849 (Print)
IS  - 0193-1849 (Linking)
VI  - 287
IP  - 6
DP  - 2004 Dec
TI  - Insulin facilitation of muscle protein synthesis following resistance exercise in 
      hindlimb-suspended rats is independent of a rapamycin-sensitive pathway.
PG  - E1070-5
AB  - Hindlimb suspension (HS) results in rapid losses of muscle mass, which may in 
      part be explained by attenuated rates of protein synthesis. Mammalian target of 
      rapamycin (mTOR) regulates protein synthesis and has been implicated as a 
      potential mediator of the muscle mass decrement with HS. This study examined the 
      effect of resistance exercise, a muscle hypertrophy stimulant, on rates of 
      protein synthesis after 4 days of HS in mature male Sprague-Dawley rats. Flywheel 
      resistance exercise (2 sets x 25 repetitions) was conducted on days 2 and 4 of HS 
      (HSRE). Sixteen hours after the last exercise bout, soleus muscles were assessed 
      for in vitro rates of protein synthesis, with and without insulin (signaling 
      agonist) and/or rapamycin (mTOR inhibitor). Results demonstrated that soleus mass 
      was reduced (P < 0.05) with HS, but this loss of mass was not observed (P > 0.05) 
      with HSRE. Muscle protein synthesis was diminished (P < 0.05) with HS, with or 
      without insulin. HSRE also had reduced rates of synthesis without insulin; 
      however, insulin administration yielded higher (P < 0.05) rates in HSRE compared 
      with HS or control. Rapamycin diminished protein synthesis in all groups (P < 
      0.05), but insulin rescued synthesis rates in HS and HSRE to levels similar to 
      insulin alone for each group, suggesting that alternate signaling pathways 
      develop to increase protein synthesis with HS. These results demonstrate that the 
      capacity for an augmented anabolic response to resistance exercise is maintained 
      after 4 days of HS and is independent of a rapamycin-sensitive pathway.
FAU - Fluckey, James D
AU  - Fluckey JD
AD  - Nutrition, Metabolism and Exercise Laboratory, University of Arkansas for Medical 
      Sciences, 4301 W. Markham, Slot 806, Little Rock, AR 72205, USA. 
      Fluckeyjamesd@uams.edu
FAU - Dupont-Versteegden, Esther E
AU  - Dupont-Versteegden EE
FAU - Knox, Micheal
AU  - Knox M
FAU - Gaddy, Dana
AU  - Gaddy D
FAU - Tesch, Per A
AU  - Tesch PA
FAU - Peterson, Charlotte A
AU  - Peterson CA
LA  - eng
GR  - AR 47577/AR/NIAMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
DEP - 20040810
PL  - United States
TA  - Am J Physiol Endocrinol Metab
JT  - American journal of physiology. Endocrinology and metabolism
JID - 100901226
RN  - 0 (Insulin)
RN  - 0 (Muscle Proteins)
RN  - EC 2.7.- (Protein Kinases)
RN  - EC 2.7.11.1 (TOR Serine-Threonine Kinases)
RN  - W36ZG6FT64 (Sirolimus)
SB  - IM
MH  - Animals
MH  - *Hindlimb Suspension
MH  - Insulin/*pharmacology
MH  - Male
MH  - Muscle Proteins/*biosynthesis
MH  - Muscle, Skeletal/anatomy & histology/*physiology
MH  - Organ Size
MH  - Physical Exertion/*physiology
MH  - Protein Kinases/drug effects/*physiology
MH  - Rats
MH  - Rats, Sprague-Dawley
MH  - Sirolimus/*pharmacology
MH  - TOR Serine-Threonine Kinases
MH  - Time Factors
OTO - NASA
OT  - Non-programmatic
EDAT- 2004/08/12 05:00
MHDA- 2004/12/17 09:00
CRDT- 2004/08/12 05:00
PHST- 2004/08/12 05:00 [pubmed]
PHST- 2004/12/17 09:00 [medline]
PHST- 2004/08/12 05:00 [entrez]
AID - 00329.2004 [pii]
AID - 10.1152/ajpendo.00329.2004 [doi]
PST - ppublish
SO  - Am J Physiol Endocrinol Metab. 2004 Dec;287(6):E1070-5. doi: 
      10.1152/ajpendo.00329.2004. Epub 2004 Aug 10.