In NF ventricles, both MAO-A and B isoforms were present with a MAO-A/MAO-B activity ratio of about 1 : 2-3-fold in both ventricles; in IHD ventricles, MAO-A and B activities increased significantly as compared to NF hearts (Figures 2(a) and 2(b)) with a similar increase of the IHD/NF ratio of MAO isoform activity in the respective ventricle (LV: MAO-A 8.40-fold; MAO-B: 7.33-fold; RV: MAO-A 5.92-fold; MAO-B 4.73-fold). Here, MAOA is linked to myocardial ischemia.