Extracellular purine catabolite and amino acid levels in the rat striatum during severe hypoglycemia: Effects of 2-amino-5-phosphonovalerate.

The effects of d-2-amino-5-phosphonovalerate on severe hypoglycemia-induced alterations in extracellular levels of amino acids and purine catabolites were examined in the rat striatum using the brain microdialysis technique. The extracellular concentrations of purine catabolites (hypoxanthine, xanthine, inosine and adenosine) increased dramatically during the isoelectric period. Following readministration of glucose, adenosine levels fell to control levels. The concentration of the other purine catabolites continued to rise to a maximum 20-40 min later. Although the concentration of hypoxanthine and inosine was reduced after 50-70 min, xanthine efflux remained elevated. Perfusion of d-2-amino-5-phosphonovalerate (1 mM) via a dialysis probe did not affect either the efflux of purine catabolites during the isoelectric period, or the maximum response observed during the recovery period. However, in d-2-amino-5-phosphonovalerate perfused striata the overflow of hypoxanthine, xanthine and inosine was significantly lower 50-70 min after glucose administration. d-2-amino-5-phosphonovalerate perfusion did not affect the extracellular overflow of amino acids during the isolectric period.