Energetic driving forces are maintained in resting rat skeletal muscle after dietary creatine supplementation

1  Exercise and Sport Research Institute, Arizona State University, Tempe, Arizona 85287; and 2  Department of Exercise Science, University of Southern California, Los Angeles, California 90089 The total creatine (TCr) pool of skeletal muscle is composed of creatine (Cr) and phosphocreatine (PCr). I...

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Published in:Journal of applied physiology (1985) 2001-01, Vol.90 (1), p.62-66
Main Authors: McMillen, J, Donovan, C. M, Messer, J. I, Willis, W. T
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Creatine - administration & dosage
Creatine - blood
Creatine - metabolism
Creatine - pharmacology
Diet
Dietary supplements
Energy Metabolism - drug effects
Feeding. Feeding behavior
Fundamental and applied biological sciences. Psychology
Male
Muscle, Skeletal - metabolism
Muscular system
Phosphates
Phosphates - metabolism
Phosphocreatine - metabolism
Rats
Rats, Sprague-Dawley
Rest - physiology
Rodents
Thermodynamics
Vertebrates: anatomy and physiology, studies on body, several organs or systems
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Summary:1  Exercise and Sport Research Institute, Arizona State University, Tempe, Arizona 85287; and 2  Department of Exercise Science, University of Southern California, Los Angeles, California 90089 The total creatine (TCr) pool of skeletal muscle is composed of creatine (Cr) and phosphocreatine (PCr). In resting skeletal muscle, the ratio of PCr to TCr (PCr/TCr; PCr energy charge) is ~0.6-0.8, depending on the fiber type. PCr/TCr is linked to the cellular free energy of ATP hydrolysis by the Cr kinase equilibrium. Dietary Cr supplementation increases TCr in skeletal muscle. However, many previous studies have reported data indicating that PCr/TCr falls after supplementation, which would suggest that Cr supplementation alters the resting energetic state of myocytes. This study investigated the effect of Cr supplementation on the energy phosphates of resting skeletal muscle. Male rats were fed either rodent chow (control) or chow supplemented with 2% (wt/wt) Cr. After 2 wk on the diet, the gastrocnemius and soleus muscles were freeze clamped and removed from anesthetized animals. Cr supplementation increased TCr, PCr, and Cr levels in the gastrocnemius by 20, 22, and 17%, respectively ( P  
ISSN:8750-7587
1522-1601
DOI:10.1152/jappl.2001.90.1.62