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

Research paper by Margherita Strolin Benedetti, Thierry Boucher, Christopher J. Fowler

Indexed on: 01 Aug '83Published on: 01 Aug '83Published in: Naunyn-Schmiedeberg's Archives of Pharmacology


In both rat brain and heart, noradrenaline and 5-hydroxytryptamine are metabolised predominantly by monoamine oxidase-A. The Km 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 Ki values by the reversible inhibitors cimoxatone, toloxatone and MD 770222.