AUTOXIDATION OF DOPAMINE - A COMPARISON OF LUMINESCENT AND SPECTROPHOTOMETRIC DETECTION IN BASIC SOLUTIONS

Oxidation products of catecholamines, particularly dopamine, could pla y an important role in the physiology and pathology of the nervous sys tem. This study has therefore characterised autoxidation of dopamine m onitored in a variety of systems. Lucigenin-dependent chemiluminescenc e and reduction of cytochrome c were exploited to register generation of the byproduct superoxide anion, whereas the quinone product was det ected by a direct spectrophotometric measurement. Accumulation of hydr ogen peroxide was followed as an increase in luminol-dependent chemilu minescence. In all cases, basic solutions were used to initiate the ox idation of dopamine. The results obtained could be interpreted as spec ific reactions at the particular stages of the autoxidation process: t he luminol-dependent chemiluminescence system detected accumulation of hydrogen peroxide during dopamine oxidation, whereas the lucigenin-de pendent chemiluminescence indicated generation of superoxide anion. Fu rthermore, cytochrome c reduction, observed during dopamine oxidation, was probably attributed to a direct interaction with dopamine semiqui none. In addition, the effects of superoxide dismutase, catalase, and peroxidase were examined in each of the systems: Each enzyme exhibited a different effect in each system used. The possible reaction mechani sms leading to different action of enzymes affecting reactive oxygen s pecies are discussed. The methods described here of monitoring dopamin e autoxidation could thus be used in parallel to detect the effects of different preparations on Various stages of the dopamine autoxidation process.