Applications of LC with Electrochemical Detection to Brain Amine Studies

Applications of LC with Electrochemical Detection to Brain Amine Studies 

Traditional methods for measuring amine release from brain slices in vitro under either static or superfusion incubation conditions have relied on prelabeling the amine pool with tritiated amine. The sensitivity of LC- 

Hammond and co-workers (Hammond et al, 1980) have measured 5-HT and 5-HIAA release from the superfused spinal cord of the anesthetized rat and have shown 5-HT release to be evoked by / -chloroamphe-tamine (10 M) but decreased by the MAO inhibitor clorgyline (2 x 10 M). 

A link between the direct monitoring of amines and their metabolites in vivo (see Section 3) is provided by the work of Loullis and colleagues who have combined a push-pull cannula with LC and electrochemical detection to measure norepinephrine, dopamine, 5-HTP, 5-HT, and 5-HIAA release into perfusates collected through the cannula (Loullis et al, 1980). 

Electrochemical detection also offers an alternative approach to amine enzyme activity measurement as the assays for the precursors, the amines, and their metabolites are adequately sensitive. Modifications to the normal assay are required especially if the substrate, which will be added in excess, is electroactive and separated on the same LC column. For example, dopamine-p-hydroxylase activity is measured by incubating dopamine with the required cofactors for a fixed time and then measuring the amount of norepinephrine formed (Davis and Kissinger, 1979). However, sub- 

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