Steady-state and time-resolved quantitative microdialysis was used to measure dialysate concentration, extracellular concentration and the in vivo recovery of glucose in rat striatum. 2. The extracellular concentration of glucose, determined by the zero net flux method of Lönnroth, was 350 +/- 20 microM and the in vivo recovery was 39 +/- 2%. 3. Veratridine caused a steep decrease in dialysate glucose after an initial delay of 7.5 min. When steady-state glucose levels had been reached in the presence of veratridine the extracellular concentration was reduced to zero, but there was no significant change in in vivo recovery. 4. Measurement of the dynamic changes during the administration of veratridine showed an immediate decrease in extracellular glucose concentration and a steep rise in in vivo recovery, which accounted for the delay in the delay in the decrease in dialysate glucose. When extracellular concentration reached zero, in vivo recovery returned to control levels.
