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Title: Rat cardiac myocyte adenosine transport and metabolism

Based on the importance of myocardial adenosine and adenine nucleotide metabolism, the adenosine salvage pathway in ventricular myocytes was studied. Accurate estimates of transport rates, separate from metabolic fllux, were determined. Adenosine influx was constant between 3 and 60 s. Adenosine metabolism maintained intracellular adenosine concentrations < 10% of the extracellular adenosine concentrations and thus unidirectional influx could be measured. Myocytes transported adenosine via saturable and nonsaturable processes. A minimum estimate of the V/sub max/ of myocytic adenosine kinase indicated the saturable component of adenosine influx was independent of adenosine kinase activity. Saturable transport was inhibited by nitrobenzylthioinosine and verapamil. Extracellular adenosine taken up myocytes was rapidly phosphorylated to adenine taken up by myocytes was rapidly phosphorylated to adenine nucleotides. Not all extracellular adenosine, though, was phosphorylated on entering myocytes, since free, as opposed to protein-bound, intracellular adenosine was detected after digitonin extraction of cells in the presence of 1 mM ethylene-diaminetetraacetic acid.
Authors:
;
Publication Date:
OSTI Identifier:
6411196
Resource Type:
Journal Article
Resource Relation:
Journal Name: Am. J. Physiol.; (United States); Journal Volume: 252:1
Research Org:
Univ. of Missouri, Columbia
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ADENOSINE; MEMBRANE TRANSPORT; METABOLISM; MYOCARDIUM; BIOCHEMICAL REACTION KINETICS; TRITIUM COMPOUNDS; ANIMAL CELLS; BIOLOGICAL PATHWAYS; CARBON 14 COMPOUNDS; LIQUID COLUMN CHROMATOGRAPHY; RATS; SACCHAROSE; SCINTILLATION COUNTING; ANIMALS; BODY; CARBOHYDRATES; CARDIOVASCULAR SYSTEM; CHROMATOGRAPHY; COUNTING TECHNIQUES; DISACCHARIDES; HEART; KINETICS; LABELLED COMPOUNDS; MAMMALS; MUSCLES; NUCLEOSIDES; NUCLEOTIDES; OLIGOSACCHARIDES; ORGANIC COMPOUNDS; ORGANS; REACTION KINETICS; RIBOSIDES; RODENTS; SACCHARIDES; SEPARATION PROCESSES; VERTEBRATES 550201* -- Biochemistry-- Tracer Techniques