L‐[3H]Adenosine, a New Metabolically Stable Enantiomeric Probe for Adenosine Transport Systems in Rat Brain Synaptoneurosomes

Academic Article

Abstract

  • Abstract: The stereoenantiomers D‐[3H]adenosine and L‐[3H]adenosine were used to study adenosine accumulation in rat cerebral cortical synaptoneurosomes. L‐Adenosine very weakly inhibited rat brain adenosine deaminase (ADA) activity with a Ki value of 385 μM. It did not inhibit rat brain adenosine kinase (AK) activity, nor was it utilized as a substrate for either ADA or AK. The rate constants (fmol/mg of protein/s) for L‐[3H]adenosine accumulation measured in assays where transport was stopped either with inhibitor‐stop centrifugation or with rapid filtration methods were 82 ± 14 and 75 ± 10, respectively. Using the filtration method, the rates of L‐[3H]adenosine accumulation were not significantly different from the value of 105 ± 15 fmol/mg of protein/s measured for D‐[3H]adenosine transport. Unlabeled D‐adenosine and nitrobenzylthioinosine, both at a concentration of 100 μM, reduced the levels and rates of L‐[3H]adenosine accumulation by >44%. These findings suggest that L‐adenosine, a metabolically stable enantiomeric analog, and the naturally occurring D‐adenosine are both taken up by rat brain synaptoneurosomes by similar processes, and as such L‐adenosine may represent an important new probe with which adenosine uptake may be studied. Copyright © 1991, Wiley Blackwell. All rights reserved
  • Authors

    Published In

    Digital Object Identifier (doi)

    Author List

  • Gu JG; Delaney S; Sawka AN; Geiger JD
  • Start Page

  • 548
  • End Page

  • 552
  • Volume

  • 56
  • Issue

  • 2