Energetic status and mitochondrial oxidative capacity of rat skeletal muscle in response to creatine analogue ingestion.
A creatine analogue, beta-guanidinopropionic acid (beta-GPA), was administered in the food (1% w/w) of 8 male rats for 6 weeks, while 8 control rats received a standard diet. Mitochondrial oxidative capacity and cytosolic modulators of mitochondrial oxidative phosphorylation (free ADP, ATP-to-free ADP ratio) were evaluated in the soleus and extensor digitorum longus (EDL) muscles. Mitochondrial adaptation to the diet was significantly different between muscles. Citrate synthase activity and mitochondrial ATP synthesis rate were 35 and 45% higher in EDL muscle, respectively, whereas they were virtually unchanged in the soleus muscle. In both muscles, 3-hydroxyacyl-CoA dehydrogenase activity remained unaffected. Regardless of muscle type, creatine, phosphocreatine and ATP concentrations, as well as the total adenine nucleotide content (ATP + ADP + AMP), were significantly lower in beta-GPA fed rats. Whereas free ADP concentration remained unchanged, a significantly greater decrease in ATP-to-free ADP ratio was observed in EDL than in the soleus muscle. It is suggested that regulation of mitochondrial oxidative phosphorylation, through changes in metabolite concentrations, could be an important factor to consider for mitochondrial adaptation induced by beta-GPA feeding.
Freyssenet
D
D
Laboratoire de Physiologie-GIP Exercise, Faculté de Médecine, CHU de Saint-Etienne, Hôpital de Saint-Jean-Bonnefonds, France.
Berthon
P
P
Barthélémy
J C
JC
Busso
T
T
Geyssant
A
A
Denis
C
C
D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003401:Creatine / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects*; D006146:Guanidines / Q000494:pharmacology*; D008297:Male; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000378:metabolism*; D009929:Organ Size / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D010725:Phosphocreatine / Q000378:metabolism; D011422:Propionates / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000227:Adenine Nucleotides; D006146:Guanidines; D009124:Muscle Proteins; D011422:Propionates; D010725:Phosphocreatine; D003401:Creatine; C005775:guanidinopropionic acid