Modifications of the Brandel Superfusion 600 system and other revisions in superfusion technique improve the measurement of endogenous dopamine release in vitro

The Brandel Superfusion 600 is an automated system designed for the simultaneous measurement of neurotransmitter release from tissue slices from six chambers. In optimizing a technique for the measurement of endogenous dopamine (DA) with this system, a number of factors were identified which affected adversely both the accuracy and the precision of within and between experiments. These factors included bubbles in the perfusion chamber, an apparent loss of tissue viability during preparation of the slices, depletion of DA stores after multiple stimulations and degradation of DA in the perfusate after collection. The method was substantially improved with modifications in the Superfusion 600 system and by the addition of high Mg²⁺ to the preparation buffer. The addition of tyrosine to the perfusion buffer and the prevention of analyte degradation with antioxidant agents also improved accuracy and precision of measurements.