Measuring perfusion and bioenergetics simultaneously in mouse skeletal muscle: a multiparametric functional-NMR approach.
A totally noninvasive set-up was developed for comprehensive NMR evaluation of mouse skeletal muscle function in vivo. Dynamic pulsed arterial spin labeling-NMRI perfusion and blood oxygenation level-dependent (BOLD) signal measurements were interleaved with (31)P NMRS to measure both vascular response and oxidative capacities during stimulated exercise and subsequent recovery. Force output was recorded with a dedicated ergometer. Twelve exercise bouts were performed. The perfusion, BOLD signal, pH and force-time integral were obtained from mouse legs for each exercise. All reached a steady state after the second exercise, justifying the pointwise summation of the last 10 exercises to compensate for the limited (31)P signal. In this way, a high temporal resolution of 2.5  s was achieved to provide a time constant for phosphocreatine (PCr) recovery (τ(PCr)). The higher signal-to-noise ratio improved the precision of τ(PCr) measurement [coefficient of variation (CV) = 16.5% vs CV = 49.2% for a single exercise at a resolution of 30  s]. Inter-animal summation confirmed that τ(PCr) was stable at steady state, but shorter (89.3 ± 8.6  s) than after the first exercise (148  s, p < 0.05). This novel experimental approach provides an assessment of muscle vascular response simultaneously to energetic function in vivo. Its pertinence was illustrated by observing the establishment of a metabolic steady state. This comprehensive tool offers new perspectives for the study of muscle pathology in mice models.
Baligand
C
C
Institute of Myology, NMR Laboratory, Paris, France.
Wary
C
C
Ménard
J C
JC
Giacomini
E
E
Hogrel
J-Y
JY
Carlier
P G
PG
D000818:Animals; D004558:Electric Stimulation; D004734:Energy Metabolism; D006614:Hindlimb / Q000098:blood supply; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D008297:Male; D051379:Mice; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D010477:Perfusion; D010725:Phosphocreatine / Q000378:metabolism; D010805:Physical Conditioning, Animal / Q000502:physiology
D010725:Phosphocreatine