Fig. 4.

Inhibition of MAO with tranylcypromine (TC, 10 μM) significantly attenuated the increase in superoxide in tricuspid and pulmonary valves, and pulmonary artery homogenates incubated with 100 μM 5-HT. A specific inhibitor of MAO-A [1 μM clorgyline (Clorg)] also attenuated increases in superoxide. Vehicle was PBS at pH 7.4. P < 0.05 vs. control (*) and vs. 5-HT only-Veh (#); n = 4 for tricuspid valve, n = 6 for pulmonary valve, and n = 7 for pulmonary artery. Analysis used controls shown in Fig. 1.