title: Erythrocyte metabolism of purines and purine nucleosides during storage and simulated physiological conditions.
abstract: Some results from storage experiments at +4 degrees C with adenine and purine nucleosides in this laboratory are compared with incubation experiments at 37 degrees C with guanosine at pH 7.0 and 7.4 and different levels of inorganic phosphate (iP). At high iP concentration the synthesis of GTP was extremely rapid. Replacement of ATP by and ATP-GTP mixture has metabolic effects on several enzymic steps e.g. phosphofructose kinase and phosphoglycerate kinase explaining the reported beneficial effect on human erythrocytes during preservation. In order to explore the role of erythrocytes in the physiological transport of purines and purine nucleosides in vitro experiments were designed in which the substances were continuously added at the appropriate concentrations by means of a dialysis tubing. Analyses of purines, nucleosides, glucose, lactate and iP in the efferent dialysis solution and the extra- and intracellular volumes reveal the metabolic processes in the erythrocytes if the transport across the dialysis tubing is accounted for. Prior to incubation the erythrocytes were stored with NaF in order to reduce the total adenylate concentration. The rate of synthesis of adenylates was about 0.05 mmol x h(-1) (calculated per litre of erythrocytes) when adenine was supplied as source for the adenine moiety of adenylates but reached a five times higher substance rate when adenosine was supplied at a sufficiently high rate. Adenosine deaminase played an important role also at "sub-physiological" concentrations. The results indicate that the erythrocytes take part in the transport of purines between organs.
mesh_terms: D000227:Adenine Nucleotides / Q000097:blood; D001800:Blood Specimen Collection; D004912:Erythrocytes / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000097:blood; D006801:Humans; D007700:Kinetics; D011684:Purine Nucleosides / Q000097:blood*; D011687:Purines / Q000097:blood*
chemical_list: D000227:Adenine Nucleotides; D006150:Guanine Nucleotides; D011684:Purine Nucleosides; D011687:Purines