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Direct validation of in vivo localized 13 C MRS measurements of brain glycogen
Author(s) -
Lei Hongxia,
Morgenthaler Florence,
Yue Tianwen,
Gruetter Rolf
Publication year - 2007
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21128
Subject(s) - glycogen , in vivo , chemistry , in vitro , hypoglycemia , endocrinology , biochemistry , biology , diabetes mellitus , microbiology and biotechnology
With the use of localized 13 C MRS in conjunction with [1‐ 13 C]‐D‐glucose infusion, it is possible to study brain glycogen metabolism in vivo. The purpose of this study was to validate in vivo 13 C MRS measurements by comparing them with results from a standard biochemical assay. To increase the [1– 13 C] glycogen concentration, 11 rats were subjected to an episode of acute hypoglycemia followed by a mild hyperglycemic recovery period during which [1‐ 13 C]‐D‐glucose was infused. The total brain [1‐ 13 C] glycogen of the same animal was determined from the enzymatically determined total brain glycogen content, which was fixed by focused microwave irradiation (4 kW in 1.4 s) immediately after the end of the in vivo NMR measurements. The corresponding isotopic enrichment (IE) of glycogen was measured by in vitro 1 H MRS of protons bound to glucose C1‐α. The in vivo [1‐ 13 C] glycogen concentration was strongly correlated to the in vitro [1‐ 13 C] glycogen content determined by biochemical measurement in a linear manner (R = 0.79). The results are consistent with the notion that localized 13 C MRS measurements closely reflect 13 C glycogen content in the brain. Magn Reson Med 57:243–248, 2007. © 2007 Wiley‐Liss, Inc.