Proton NMR observation of glycogen in vivo

Our previous solution studies of the proton relaxation properties of glycogen H1 have shown significant dipolar cross–relaxation with intra‐ring H2 and inter‐ring H4′ protons characterized by a correlation time τ_c= 2.7 × 10⁻⁹ s. This leads to a significant negative Nuclear Overhauser Enhancement (NOE) of glycogen H1 following either transient or steady state perturbations of the longitudinal magnetization of dipolar coupled protons, especially H2 and H4′. Here we use the NOE to edit selectively the H1 resonance of glycogen in the rat liver in vivo using a surface coil probe. The approach shows the possibility of measuring glycogen in vivo with high sensitivity using ¹H NMR.