Whole blood monoamine oxidase activity in Parkinson's disease and multiple system atrophy patients.

Monoamine oxidase type B (MAO-B), which catalyses the breakdown of dopamine (DA) in human brain, is said to be involved in the pathophysiology of Parkinson's disease (PD). Activity of MAO-B in PD has been measured in platelets isolated from blood samples in different studies, with contradictory results, possibly due to the differences in substrate used or to differences in platelet isolation. Therefore we measured MAO activity in whole blood, which is almost identical to MAO-B activity in platelets, in 25 drug-naive PD patients, 25 treated PD patients, 9 multiple system atrophy (MSA) patients and 20 controls, using a spectrofluorimetric method with kynuramin as a substrate. No statistically significant differences between groups were found, nor any correlation with the severity or duration of the disease.