[Properties of monoamine oxidases from myocardial mitochondria]

Mitochondrial monoamine oxidases from rabbit and rat heart muscles varied distinctly in the sensitivity to the effect of selective irreversible inhibitors clorgyline and deprenyl. In presence of mitochondrial fragments from rabbit heart oxidation of phenylethylamine, tyramine, benzylamine and triptamine was highly sensitive to the effect of deprenyl. Very low concentrations of clorgyline inhibited oxidation of these amines in samples containing rat heart mitochondrial fragments. Rabbit heart mitochondrial fragments appear to contain considerable amounts of monoamine oxidases of "B" type and rat heart mitochondrial fragments--the monoamine oxidases of "A" type. A highly sensitive fluorescent method was used for estimation of the monoamine oxidase activity; it was based on the extinguishing by hydrogen peroxide in presence of peroxidase of the scopolethine fluorescence.