title: Effect of creatine supplementation on creatine and glycogen content in rat skeletal muscle.
abstract: The effects of high dose creatine feeding (5 g kg(-1) BW day(-1), 5 days) on creatine content, glucose transport, and glycogen accumulation in white gastrocnemius, red gastrocnemius and soleus muscles of the rat was investigated. Isolated rat hindquarters of creatine fed and control rats were perfused with a standard medium containing either insulin alone (0, 100 or 20 000 microU mL(-1)) or in combination with creatine (2 or 10 mmol L(-1)). Furthermore, plasma insulin concentration was measured in normal rats during creatine feeding, as well as in anaesthetized rats during intravenous creatine infusion. Five days of creatine feeding increased (P < 0.05) total creatine content in soleus (+ 20%) but not in red gastrocnemius (+15%, n.s.) and white gastrocnemius (+ 10%, n.s.). In parallel, glycogen content was markedly elevated (P < 0.05) in soleus (+ 40%), less (P < 0.05) in red gastrocnemius (+ 15%), and not in white gastrocnemius (+ 10%, n.s.). Glucose transport rate, muscle GLUT-4 content, glycogen synthase activity in perfused muscles and glycogen synthesis rate were not significantly altered by creatine feeding in either muscle type. Furthermore, high dose creatine feeding raised (P < 0.05) plasma creatine concentration fivefold but did not alter circulating insulin level. It is concluded that short-term high dose creatine feeding enhances creatine disposal and glycogen storage in rat skeletal muscle. However, the creatine and glycogen response to creatine supplementation is markedly greater in oxidative than in glycolytic muscles.
authors.affiliation: Faculty of Physical Education and Physiotherapy, Department of Kinesiology, Katholieke Universiteit Leuven, Belgium.
authors.forename: B O
authors.initials: BO
authors.lastname: Eijnde
authors.forename: E A
authors.initials: EA
authors.lastname: Richter
authors.forename: J C
authors.initials: JC
authors.lastname: Henquin
authors.forename: B
authors.initials: B
authors.lastname: Kiens
authors.forename: P
authors.initials: P
authors.lastname: Hespel
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003401:Creatine / Q000008:administration & dosage* / Q000378:metabolism*; D004032:Diet; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4; D006003:Glycogen / Q000378:metabolism*; D006006:Glycogen Synthase / Q000378:metabolism; D006614:Hindlimb; D007328:Insulin / Q000008:administration & dosage / Q000097:blood; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D018656:Muscle Fibers, Fast-Twitch / Q000187:drug effects / Q000378:metabolism; D018657:Muscle Fibers, Slow-Twitch / Q000187:drug effects / Q000378:metabolism; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495694:Slc2a4 protein, rat; D006003:Glycogen; D006006:Glycogen Synthase; D005947:Glucose; D003401:Creatine