• 1
    The adenosine uptake blocker propentofylline (HWA 285) has previously been shown to protect hippocampal CA1 pyramidal cells from ischaemia-induced delayed neuronal death. The influence of propentofylline, on the extracellular concentrations of purines, aspartate and glutamate in the CA1 of the rat hippocampus during transient forebrain ischaemia was investigated.
  • 2
    Twenty min of ischaemia was induced by four-vessel occlusion in Wistar rats, extracellular compounds were sampled by use of microdialysis and EEG was recorded by a tungsten electrode attached to the dialysis probe.
  • 3
    Propentofylline (10 mgkg−1 i.p.) did not influence the basal levels of any of the compounds in the hippocampal dialysates.
  • 4
    The EEG became isoelectric within 20 s after induction of ischaemia.
  • 5
    Extracellular adenosine, inosine, hypoxanthine, aspartate and glutamate increased several fold during ischaemia and remained elevated during early reflow. Within 2 h of reperfusion the concentration of all compounds was normalized. Xanthine increased upon reperfusion and remained elevated after 2 h.
  • 6
    Propentofylline (10 mg kg−1 i.p.) administered 15 min before ischaemia significantly enhanced the ischaemia-evoked increase of adenosine but attenuated the increases of the other purine catabolites and of glutamate.
  • 7
    In separate in vitro experiments, propentofylline did not inhibit adenosine deaminase activity.
  • 8
    The present data show that propentofylline enhances extracellular adenosine and lowers extracellular glutamate in vivo during ischaemia. These findings may be important in relation to the neuroprotective properties of propentofylline.