Dexamethasone impairs muscle energetics, studied by (31)P NMR, in rats.
OBJECTIVE
Glucocorticoid treatments are associated with increased whole-body oxygen consumption. We hypothesised that an impairment of muscle energy metabolism can participate in this increased energy expenditure.


METHODS
To investigate this possibility, we have studied muscle energetics of dexamethasone-treated rats (1.5 mg kg(-1) day(-1) for 6 days), in vivo by (31)P NMR spectroscopy. Results were compared with control and pair-fed (PF) rats before and after overnight fasting.


RESULTS
Dexamethasone treatment resulted in decreased phosphocreatine (PCr) concentration and PCr:ATP ratio, increased ADP concentration and higher PCr to gamma-ATP flux but no change in beta-ATP to beta-ADP flux in gastrocnemius muscle. Neither 4 days of food restriction (PF rats) nor 24 h fasting affected high-energy phosphate metabolism. In dexamethasone-treated rats, there was an increase in plasma insulin and non-esterified fatty acid concentration.


CONCLUSIONS
We conclude that dexamethasone treatment altered resting in vivo skeletal muscle energy metabolism, by decreasing oxidative phosphorylation, producing ATP at the expense of PCr.
Dumas
J-F
JF
Inserm EMI-U 00.18, Laboratoire de Biochimie et de Biologie Moléculaire, CHU, 4 rue Larrey, 49033 Angers Cedex, France.
Bielicki
G
G
Renou
J-P
JP
Roussel
D
D
Ducluzeau
P-H
PH
Malthièry
Y
Y
Simard
G
G
Ritz
P
P
D020155:3-Hydroxybutyric Acid / Q000097:blood; D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology*; D004734:Energy Metabolism / Q000187:drug effects*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology*; D010101:Oxygen Consumption / Q000187:drug effects; D010710:Phosphates / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D051381:Rats; D017207:Rats, Sprague-Dawley
D000227:Adenine Nucleotides; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D020738:Leptin; D010710:Phosphates; D010761:Phosphorus Radioisotopes; D010725:Phosphocreatine; D003907:Dexamethasone; D020155:3-Hydroxybutyric Acid