Rapid on-line microdialysis hyphenated technique for the dynamic monitoring of extracellular pyruvate, lactic acid and ascorbic acid during cerebral ischemia

Rapid on-line microdialysis coupled with liquid chromatography was develope d for the continuous monitoring of brain neurochemicals during cerebral isc hemia. Isocratic separation of these analytes was achieved within 3 min, he nce, over 80 analyses could be performed in a 4-h experiment. The dead volu me of the microdialysis system was estimated to be less than 10 mu l. The d etection limits of the present assay, at a signal-to-noise ratio of five, w ere 2.0, 0.2 and 0.5 mu M, for lactic acid, pyruvate and ascorbic acid, res pectively. To validate this assay, a transient ischemia was produced by occ lusion of two common carotid arteries for 10 min in an anesthetized gerbil. A microdialysis probe was inserted into the striatum of the gerbil to simu ltaneously monitor pyruvate, lactic acid and ascorbic acid during cerebral ischemia. Significant and dynamic changes in these analytes could be resolv ed in 3-min intervals. This rapid assay can be used as a tool to study dyna mic changes in neurochemicals of the brain, such as during cerebral ischemi a. (C) 1999 Elsevier Science B.V. All rights reserved.