Ordered synthesis and mobilization of glycogen in the perfused heart

Journal Article · Tue Dec 12 04:00:00 EST 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00451a033· OSTI ID:6921673

Brainard, J R; Hutson, J Y ^[1]; Hoekenga, D E; Lenhoff, R ^[2]

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1. Los Alamos National Lab., NM (USA)
2. Veterans Administration Medical Center, Albuquerque, NM (USA)

The molecular order of synthesis and mobilization of glycogen in the perfused heart was studied by {sup 13}C NMR. By varying the glucose isotopomer ((1-{sup 13}C)glucose or (2-{sup 13}C)glucose) supplied to the heart, glycogen synthesized at different times during the perfusion was labeled at different carbon sites. Subsequently, the in situ mobilization of glycogen during ischemia was observed by detection of labeled lactate derived from glycolysis of the glucosyl monomers. When (1-{sup 13}C)glucose was given initially in the perfusion and (2-{sup 13}C)glucose was given second, (2-{sup 13}C)lactate was detected first during ischemia and (3-{sup 13}C)lactate second. This result, and the equivalent result when the glucose labels were given in the reverse order, demonstrates that glycogen synthesis and mobilization are ordered in the heart, where glycogen is found morphologically only as {beta} particles. Previous studies of glycogen synthesis and mobilization in liver and adipocytes have suggested that the organization of {beta} particles into {alpha} particles was partially responsible for ordered synthesis and mobilization. The observations reported here for cardiac glycogen suggest that another mechanism is responsible. In addition to examine the ordered synthesis and mobilization of cardiac glycogen, the authors have selectively monitored the NMR properties of {sup 13}C-labeled glycogen synthesized early in the perfusion during further glycogen synthesis from a second, differently labeled substrate. During synthesis from the second labeled glucose monomer, the glycogen resonance from the first label decreased in integrated intensity and increased in line width. These results suggest either that there is significant isotopic exchange of glucosyl monomers in glycogen during net synthesis or that glucosyl residues incorporated into glycogen undergo motional restrictions as further glycogen synthesis occurs.

• OSTI ID: 6921673
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 28:25; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL TISSUES
ANIMALS
BIOSYNTHESIS
BODY
CARBOHYDRATES
CARBON 13
CARBON ISOTOPES
CARBOXYLIC ACIDS
CARDIOVASCULAR DISEASES
CARDIOVASCULAR SYSTEM
DISEASES
EVEN-ODD NUCLEI
GLYCOGEN
GUINEA PIGS
HEART
HYDROXY ACIDS
ISCHEMIA
ISOTOPES
LABELLED COMPOUNDS
LACTIC ACID
LIGHT NUCLEI
MAGNETIC RESONANCE
MAMMALS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PERFUSED TISSUES
POLYSACCHARIDES
RESONANCE
RODENTS
SACCHARIDES
STABLE ISOTOPES
SYNTHESIS
TISSUES
VASCULAR DISEASES
VERTEBRATES