In this study, 12 new 3,6-dimethyl-9-aryl-3,4,6,7-tetrahydroacridine-1,8(2H,5H,9H,10H)-diones derivatives were synthesized. Synthesis of the compounds was realized by the reaction of 5-methyl-1,3-cyclohexanedione, the appropriate aromatic aldehyde, and ammonium acetate in methanol. The structure of the compounds was elucidated by infrared (IR), H-1-nuclear magnetic resonance (NMR), C-13-NMR, mass spectroscopy, and elemental analysis. Functional effects of the compounds on vascular potassium channels and mechanism of phenylephrine-induced contractile responses were investigated in isolated rat aorta rings. Pinacidil was used as a standard potassium channel opener.