NMR visibility of deuterium-labeled liver glycogen in vivo.

PURPOSE: Deuterium metabolic imaging (DMI) combined with [6,6'-2 H2 ]-glucose has the potential to detect glycogen synthesis in the liver. However, the similar chemical shifts of [6,6'-2 H2 ]-glucose and [6,6'-2 H2 ]-glycogen in the 2 H NMR spectrum make unambiguous detection and separation difficult in vivo, in contrast to comparable approaches using 13 C MRS. Here the NMR visibility of 2 H-labeled glycogen is investigated to better understand its potential contribution to the observed signal in liver following administration of [6,6'-2 H2 ]-glucose.
METHODS: Mice were provided drinking water containing 2 H-labeled glucose. High-resolution NMR analyses was performed of isolated liver glycogen in solution, before and after the addition of the glucose-releasing enzyme amyloglucosidase.
RESULTS: 2 H-labeled glycogen was barely detectable in solution using 2 H NMR because of the very short T2 (<2 ms) of 2 H-labeled glycogen, giving a spectral line width that is more than five times as broad as that of 13 C-labeled glycogen (T2 = ~10 ms).
CONCLUSION: 2 H-labeled glycogen is not detectable with 2 H MRS(I) under in vivo conditions, leaving 13 C MRS as the preferred technique for in vivo detection of glycogen.