The deamination of noradrenaline and 5-hydroxytryptamine by rat brain and heart monoamine oxidase and their inhibition by cimoxatone, toloxatone and MD 770222

Abstract
In both rat brain and heart, noradrenaline and 5-hydroxytryptamine are metabolised predominantly by monoamine oxidase-A. The K m values for 14C-noradrenaline in the rat brain and heart are 290 μM and 300 μM, respectively, whereas for 14C-5-hydroxytryptamine the values are 180 μM and 140 μM, respectively. In the rat brain, mixed substrate experiments suggested that 14C-noradrenaline and 14C-5-hydroxytryptamine are metabolised at the same active centre. Both substrates are inhibited with similar K i values by the reversible inhibitors cimoxatone, toloxatone and MD 770222.