“In the presence of ICI-118,551, theophylline , an inhibitor of cyclic adenosine monophosphate (cAMP)-dependent phosphodiesterase (cAMP-PDE), markedly inhibited the potentiating effect of genistein on the isoproterenol-induced relaxation, whereas in the presence of atenolol, theophylline only partly inhibited the potentiating effect of genistein.”