Effects of different perfusion medium on the extracellular basal concentration of dopamine in striatum and medial prefrontal cortex: a zero-net flux microdialysis study.

The zero-net flux microdialysis method was used to determine (1) the basal concentration of dopamine (DA) in the extracellular space, and (2) the in vivo recovery of Da in the striatum and the medial prefrontal cortex by using three different kinds of perfusion medium. They were, (a) commercial Ringer's solution, (b) low Ca2+ Ringer's solution, and (c) artificial cerebrospinal fluid (aCSF). Our results not only support previous findings that the high Ca2+ concentration in the perfusion medium could increase the baseline concentration of DA in the dialysate, which was collected from extracellular space through dialysis probe; but also provides evidence that this baseline increase was primarily due to an increase of basal DA concentration, and not from the increase of the in vivo recovery. Additionally, there was no significant difference in the basal DA concentration by using either commercial Ringer's solution or aCSF. This indicates that both commercial Ringer's solution and aCSF are suitable as good perfusion medium to determine the basal DA in the rat's brain.