In vivo 31P NMR assessed effects of dantrolene on mechanics and energy metabolism in tetanic stimulated rat gastrocnemius.
Dantrolene does not affect fatigue from submaximal effort and MVC while it decreases twitch tension. We hypothesize that dantrolene could modify the relation between energy metabolism and fatigue by inhibiting calcium release from the sarcoplasmic reticulum. The effects of dantrolene (10 mg) on mechanical and metabolic parameters of gastrocnemius muscle were examined by 31P NMR during an in vivo fatigue test. The fatigue test constituted of three successive 20 min periods of increased stimulation rhythms and followed by a 20 min recovery period. 31P NMR was used to determine phosphocreatine (PCr), ATP and intracellular pH changes, while tension was recorded. We showed that dantrolene increased mechanical fatigue while PCr levels were similar to those from control animals. Acidosis was most prominent in dantrolene treated rats. These results suggest that dantrolene firstly affects calcium cycling with additive effects to fatigue and, secondly, modifies the activation of oxidative metabolism and the energy cost of the generated tension.
Le Jeune
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N
Laboratoire de RMN en Biologie et Médecine (LRMBM), Rennes, France.
Le Rumeur
E
E
Lacroix
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P
de Certaines
J D
JD
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003620:Dantrolene / Q000494:pharmacology*; D004558:Electric Stimulation; D004734:Energy Metabolism / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009132:Muscles / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D010710:Phosphates / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D010758:Phosphorus; D051381:Rats; D017208:Rats, Wistar
D010710:Phosphates; D010725:Phosphocreatine; D010758:Phosphorus; D000255:Adenosine Triphosphate; D003620:Dantrolene