Hermien E. Kan1, Joep van Oorschot2,
Beatrijs H.A. Wokke3, Maarten J. Versluis1, Nadine B.
Smith1, Andrew G. Webb1, Jeroen A.L. Jeneson2
1C.J. Gorter Center, department of
radiology, Leiden University Medical Center, Leiden, Netherlands; 2Biomedical
NMR Laboratory, Department of Biomedical Engineering, Eindhoven University of
Technology, Eindhoven, Netherlands; 3Department of neurology,
Leiden University Medical Center, Leiden, Netherlands
Non-invasive
determination of mitochondrial content is an important objective in clinical
and sports medicine. Previously, a peak 0.4 ppm downfield from the cytosolic
Pi resonance (Pi1) was found in resting skeletal muscle that was
tentatively attributed to mitochondrial Pi (Pi2). Here we show a
consistently higher Pi2 signal in soleus (SOL) versus tibialis
anterior (TA) muscle, as well as in trained versus untrained subjects. Since
these results are in quantitative agreement with known differences in
oxidative capacity between SOL and TA and trained versus untrained subjects,
they support our hypothesis that the Pi2 resonance originates from
the mitochondrial compartment in muscle.