Use of superfused rat skeletal muscle for metabolic studies: assessment of pH by 31P n.m.r.
We developed a muscle superfusion system suitable for metabolic studies of small isolated rat muscle ex vivo in real time and in a non-destructive manner by n.m.r. spectroscopy. In order to determine biochemical stability of superfused extensor digitorum longus (EDL) muscle (from fasted 45 and 100 g rats), the energy state and the pH of muscle were continuously monitored by 31P n.m.r. spectroscopy. ATP and phosphocreatine remained stable during 2 h whatever the muscle size (20 or 45 mg). Neither metabolite was a sensitive probe of possible metabolic compartmentation within muscle under our experimental conditions. By contrast, the chemical shift of Pi by its sensitivity to pH was a discriminant factor in the assessment of muscle stability. Indeed, heterogeneity of pH was observed only in the 45 mg EDL muscle resulting from a core region with loss of glycogen. Together, these observations suggest deviations of energy metabolism to supply ATP. Consequently, pH may be considered as a new real-time criterion for monitoring a metabolic heterogeneity due to changes in energy metabolism of muscle preparations ex vivo.
Meynial-Denis
D
D
Laboratoire d'Etude du Metabolisme Azoté, INRA, Centre de Recherches de Clermont-Ferrand-Theix, Ceyrat, France.
Mignon
M
M
Foucat
L
L
Bonnet
Y
Y
Bielicki
G
G
Renou
J P
JP
Lacourt
P
P
Lacourt
A
A
Arnal
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004734:Energy Metabolism; D005260:Female; D006003:Glycogen / Q000378:metabolism; D006651:Histocytochemistry; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D009132:Muscles / Q000378:metabolism*; D010477:Perfusion / Q000379:methods; D010725:Phosphocreatine / Q000378:metabolism; D010759:Phosphorus Isotopes; D051381:Rats; D017208:Rats, Wistar
D010759:Phosphorus Isotopes; D010725:Phosphocreatine; D000255:Adenosine Triphosphate; D006003:Glycogen