Adenosine extracellular levels in human brain gliomas: an intraoperative microdialysis study.

Adenosine present in human brain glioma extracellular spaces is a marker of astrocyte purine metabolism. In this study, we evaluated adenosine levels in the extracellular fluid of 21 human gliomas of high-grade malignancy using brain microdialysis techniques coupled to high-performance liquid chromatography. The adenosine concentration (mean +/- SEM) within the control tissue was 2.99 +/- 0.37 muM and in the tumour tissue 1.56 +/- 0.46 muM. The reduction was statistically significant. It is concluded that the adenosine concentrations reached in the tumour tissue are sufficient to stimulate all adenosine receptor subtypes, suppress local anti-tumour immune responses and affect glial and endothelial cell proliferation. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.