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Adenosine Metabolism in a Rat Hippocampal Slice Preparation: Incorporation into S ‐Adenosylhomocysteine

1983; Wiley; Volume: 40; Issue: 1 Linguagem: Inglês

10.1111/j.1471-4159.1983.tb12684.x

1471-4159

Martin Reddington, Renate Pusch,

Pharmacological Effects and Toxicity Studies

Abstract: The incorporation of [ 14 C]adenosine into various metabolites was studied in a hippocampal slice preparation in order to assess the extent of adenosine metabolism via synthesis of S ‐adenosylhomocysteine, a potent inhibitor of transmethylation reactions. Highest incorporation of 14 C occurred into nucleotides, with only a few percent being recovered in inosine + hypoxanthine, S ‐adenosylhomocysteine, and the free adenosine pool. Labeling of S ‐adenosylhomocysteine did not significantly increase with higher concentrations of added adenosine despite greater accumulation of free [ 14 C]adenosine in the tissue. Addition of l ‐homocysteine significantly increased the labelling of S ‐adenosylhomocysteine. The results indicate that S ‐adenosylhomocysteine synthesis is a minor pathway of adenosine metabolism in brain tissue under steady‐state conditions. Further, changes in adenosine concentration, without a concomitant change in l ‐homocysteine availability, are unlikely to lead to a significant accumulation of S ‐adenosylhomocysteine. S ‐Adenosylhomocysteine is therefore not likely to play a significant role in mediating the biological effects of adenosine in the CNS via inhibition of transmethylations.