NMR visibility of deuterium-labeled liver glycogen in vivo.

PURPOSE

Deuterium metabolic imaging (DMI) combined with [6,6'- H ]-glucose has the potential to detect glycogen synthesis in the liver. However, the similar chemical shifts of [6,6'- H ]-glucose and [6,6'- H ]-glycogen in the H NMR spectrum make unambiguous detection and separation difficult in vivo, in contrast to comparable approaches using C MRS. Here the NMR visibility of H-labeled glycogen is investigated to better understand its potential contribution to the observed signal in liver following administration of [6,6'- H ]-glucose.

METHODS

Mice were provided drinking water containing 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

H-labeled glycogen was barely detectable in solution using H NMR because of the very short T (<2 ms) of H-labeled glycogen, giving a spectral line width that is more than five times as broad as that of C-labeled glycogen (T = ~10 ms).

CONCLUSION

H-labeled glycogen is not detectable with H MRS(I) under in vivo conditions, leaving C MRS as the preferred technique for in vivo detection of glycogen.