Selective inhibition by amezinium of intraneuronal monoamine oxidase

Intra- and extraneuronal compartments of rat hearts were selectively labelled by perfusion with 3H-noradrenaline in the presence of corticosterone 87 microM or cocaine 30 microM, respectively. The subsequent outflow of 3H-compounds was examined. As little as 1 nM amezinium diminished the outflow of intraneuronally formed 3H-DOPEG. This effect was antagonized by cocaine. Amezinium 1 microM was necessary to diminish the outflow of extraneuronally formed 3H-DOPEG. This effect was not counteracted by corticosterone. The results indicate that amezinium is both a potent and, at low concentrations, selective inhibitor of intraneuronal MAO.