In this study, 1;2 new 2,2,7,7-tetramethyl-9-aryl-2,3,4,5,6,7,9,10-octahydro-1,8-acridindione derivatives were synthesised and. their effects on vascular potassium channels and mechanism of induced relaxations on phenylephrine-induced contractile responses in isolated rabbit thoracic arteries was investigated. Pinacidil was used as standard potassium channel openers in this study. Compounds 1-12 and pinacidil exerted concentration-dependent relaxation responses precontracted phenylephrine in the aortic rings with the efficacy order: 11 > pinacidil > 7 > 2 > 8 > 3 > 1 > 4 > 10 > 6 > 9 > 5 > 12. (C) 2002 Published by Editions scientifiques et medicales Elsevier SAS.