CHANGES IN CEREBRAL BLOOD-FLOW DO NOT DIRECTLY AFFECT INVIVO RECOVERY OF EXTRACELLULAR LACTATE THROUGH MICRODIALYSIS PROBE

Influence of striatal blood flow changes on recovery of extracellular lactate in vivo through a microdialysis probe implanted into the neostriatum was investigated in halothane anesthetized rats. Relative radioactivity loss of [C-14]lactate from perfusate medium through a microdialysis probe was continuously measured in vivo as an indicator of relative recovery of extracellular lactate through the probe because both the relative recovery of lactate and the relative hot loss of [C-14]lactate through a microdialysis probe were similar to each other in vitro. The relative hot loss of [C-14]lactate decreased in parallel with decreases in the striatal blood flow, while it did not significantly change in response to increases in the blood flow up to 200% of control. These results demonstrate that recovery of extracellular lactate in vivo through the microdialysis probe is not directly influenced by changes in the cerebral blood flow.