Evidence for a 'metabolically inactive' inorganic phosphate pool in adenosine triphosphate synthase reaction using localized 31P saturation transfer magnetic resonance spectroscopy in the rat brain at 11.7 T

International audience; With the increased spectral resolution made possible at high fields, a second, smaller inorganic phosphate resonance can be resolved on $^{31}$P magnetic resonance spectra in the rat brain. Saturation transfer was used to estimate de $novo$ adenosine triphosphate synthesis reaction rate. While the main inorganic phosphate pool is used by adenosine triphos-phate synthase, the second pool is inactive for this reaction. Accounting for this new pool may not only help us understand $^{31}$P magnetic resonance spectroscopy metabolic profiles better but also better quantify adenosine triphos-phate synthesis.