Noninvasive Measurements of [1‐13C] Glycogen Concentrations and Metabolism in Rat Brain In Vivo

• Published in: Journal of neurochemistry 1999-09, Vol.73 (3), p.1300-1308
• Main Authors: Choi, In‐Young, Tkáčc, Ivan, Ugurbil, Kâmil, Gruetter, Rolf
• Format: Article
• Language: English
• Subjects: Animals; Biochemistry and metabolism; Biological and medical sciences; Brain - metabolism; Carbon Isotopes; Central nervous system; Fundamental and applied biological sciences. Psychology; Glucose - metabolism; Glucose transport; Glycogen - metabolism; Glycogen phosphorylase; Glycogen synthase; Glycogen Synthase - metabolism; Hyperglycemia - metabolism; In vivo studies; Magnetic Resonance Spectroscopy; Male; NMR; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Spectroscopy; Vertebrates: nervous system and sense organs
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1046/j.1471-4159.1999.0731300.x

: Using a specific 13C NMR localization method, 13C label incorporation into the glycogen C1 resonance was measured while infusing [1‐13C]glucose in intact rats. The maximal concentration of [1‐13C]glycogen was 5.1 ± 0.6 μmol g‐1 (mean ± SE, n = 8). During the first 60 min of acute hyperglycemia, the rate of 13C label incorporation (synthase flux) was 2.3 ± 0.7 μmol g‐1 h‐1 (mean ± SE, n = 9 rats), which was higher (p 0.05 for correlation). The results implied that net glycogen synthesis of ~3 μmol g‐1 had occurred, similar to previous reports. When infusing unlabeled glucose before [1‐13C]glucose in three studies, the rate of glycogen C1 accumulation was 0.46 ± 0.08 μmol g‐1 h‐1. The results suggest that steady‐state glycogen turnover rates during hyperglycemia are ~1% of glucose consumption.