Document Detail

Effects of long-term creatine feeding and running on isometric functional measures and myosin heavy chain content of rat skeletal muscles.
MedLine Citation:
PMID:  16688465     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to investigate whether creatine (Cr) supplementation during 12 weeks of phasic high-frequency voluntary wheel running would result in a faster myosin heavy chain (MHC) isoform profile in the rat mixed fast-twitch plantaris and alter its corresponding isometric contractile properties. The fast-twitch extensor digitorum longus and medial gastrocnemius and slow-twitch soleus were also studied. Forty weanling Sprague-Dawley male rats were assigned to one of four groups: creatine-sedentary (Cre-Sed); creatine-voluntary running (Cre-Run); control-sedentary (Con-Sed); control-voluntary running (Con-Run). Daily running distance was similar between Cre-Run and Con-Run. Average daily Cr ingestion was also similar being 2.4+/-0.17 and 3.0+/-0.14 g/kg in Cre-Sed and Cre-Run, respectively. Total creatine (TCr) content was elevated (P<0.03) in the plantaris of Cre-Run [211.4+/-16.9 mmol/kg dry weight (dw)], compared with Con-Run (175.1+/-5.69). In the plantaris, MHCIIb was 13% greater (P<0.00001) in Cre-Run compared with Con-Run, while MHCIId/x and MHCIIa were lower in Cre-Run by 7 and 6% (P<0.0002), respectively. No differences were observed in twitch force, time-to-peak tension, half-rise time or half-fall time. Greater tetanic force production (P<0.05) in Cre-Sed compared with Con-Sed corresponded to a 12% increase in MHCIId/x (P<0.0001) and a 12% decrease in MHCIIb (P<0.0006). The fatigue index of the plantaris at 10 s (FI(10s)) was reduced only after running (Cre-Run vs Con-Run), while in all other muscles the FI(10s) was lower only in the Cre-Sed group. In conclusion, Cr supplementation had differential effects on MHC isoform content and fatigability that depended on the level of contractile activity. Cr feeding combined with running exercise resulted in a faster MHC-based phenotype in the rat plantaris but the impact on associated isometric contractile properties was minimal.
Maria Gallo; Tessa Gordon; Daniel Syrotuik; Yang Shu; Neil Tyreman; Ian MacLean; Zoltan Kenwell; Charles T Putman
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-05-11
Journal Detail:
Title:  Pflügers Archiv : European journal of physiology     Volume:  452     ISSN:  0031-6768     ISO Abbreviation:  Pflugers Arch.     Publication Date:  2006 Sep 
Date Detail:
Created Date:  2006-09-01     Completed Date:  2007-01-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0154720     Medline TA:  Pflugers Arch     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  744-55     Citation Subset:  IM    
Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation, University of Alberta, Edmonton T6G 2H9, Alberta, Canada.
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MeSH Terms
Adenosine Diphosphate / metabolism
Adenosine Monophosphate / metabolism
Adenosine Triphosphate / metabolism
Body Weight / physiology
Creatine / pharmacology*
Eating / physiology
Hindlimb / physiology
Isometric Contraction / drug effects*
Muscle Contraction / drug effects,  physiology
Muscle Fatigue / drug effects,  physiology
Muscle, Skeletal / drug effects,  metabolism,  physiology*
Myosin Heavy Chains / metabolism*
Organ Size / physiology
Physical Conditioning, Animal / physiology
Rats, Sprague-Dawley
Running / physiology*
Reg. No./Substance:
0/Myosin Heavy Chains; 56-65-5/Adenosine Triphosphate; 57-00-1/Creatine; 58-64-0/Adenosine Diphosphate; 61-19-8/Adenosine Monophosphate

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