On-line Monitoring of Cerebral pH by Microdialysis

AN ON-LINE pH meter that can be mounted in microdialysis systems is described. The pH monitoring system was tested in rat cortex before and after middle cerebral artery occlusion (focal ischemia model). After probe implantation, pH values in the dialysate quickly reached a stable level that depended on perfusion medium (6.72, Ringer; 6.47, 0.9% saline) and flow rate (2 μl/min). During ischemia, pH values sank rapidly and significantly, whereas...