Free creatine available to the creatine phosphate energy shuttle in isolated rat atria

Journal Article · Sat Oct 01 00:00:00 EDT 1988 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.85.20.7476· OSTI ID:5547028

Savabi, F ^[1]

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1. Univ. of Southern California School of Medicine, Los Angeles (USA)

To measure the actual percentage of intracellular free creatine participating in the process of energy transport, the incorporation of (1-{sup 14}C)creatine into the free creatine and phosphocreatine (PCr) pools in spontaneously beating isolated rat atria, under various conditions, was examined. The atria were subjected to three consecutive periods, control, anoxia, and postanoxic recover, in medium containing tracers of (1-{sup 14}C)creatine. The tissue content and specific activity of creatine and PCr were determined at the end of each period. The higher specific activity found for tissue PCr (1.87 times) than creatine, independent of the percentage of total intracellular creatine that was present as free creatine, provides evidence for the existence of two separate pools of free creatine. Analysis of the data shows that in the normal oxygenated state {approx} 9% of the total intracellular creatine is actually free to participate in the process of energy transport (shuttle pool). About 36% of the total creatine is bound to unknown intracellular components and the rest exists as PCr. The creatine that was taken up and the creatine that was released from the breakdown of PCr have much greater access to the site of phosphorylation than the rest of the intracellular creatine. A sharp increase in the specific activity of residual PCr on prolongation of anoxic time was also observed. This provides evidence for a nonhomogeneous pool of PCr, for the most recently formed (radioactive) PCr appeared to be hydrolyzed last.

• OSTI ID: 5547028
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Vol. 85:20; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CARBON 14 COMPOUNDS
UPTAKE
CREATINE
HEART
BIOLOGICAL PATHWAYS
ANOXIA
GLUCOSE
OXYGEN
PHOSPHOCREATINE
PHYSIOLOGY
RATS
ALDEHYDES
AMINO ACIDS
ANIMALS
BODY
CARBOHYDRATES
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
ELEMENTS
HEXOSES
LABELLED COMPOUNDS
MAMMALS
MONOSACCHARIDES
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANS
RODENTS
SACCHARIDES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques