[3H]Harman labels selectively and with high affinity the active site of monoamine oxidase (EC 1.4.3.4) subtype A (MAO-A) in rat, marmoset, and pig.

[3H]Harman was used in binding studies with CNS tissue of rat, pig, and marmoset and with visceral organs of the rat. In the mitochondrial fractions of the CNS of the 3 species [3H]harman binding exhibits the same pharmacological profile in displacement studies. A detailed analysis reveals a high specificity for MAO-A. Furthermore, we applied [3H]harman binding to quantify the MAO-A content in 6 CNS regions of each species as well as in 6 visceral organs of the rat.