4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone: Inhibitor of phosphodiesterases.Imidazolidines: Compounds based on reduced IMIDAZOLINES which contain no double bonds in the ring.Receptors, Epoprostenol: Cell surface receptors for EPOPROSTENOL. They are coupled to HETEROTRIMERIC G-PROTEINS.Mannosides: Glycosides formed by the reaction of the hydroxyl group on the anomeric carbon atom of mannose with an alcohol to form an acetal. They include both alpha- and beta-mannosides.Imidazoles: Compounds containing 1,3-diazole, a five membered aromatic ring containing two nitrogen atoms separated by one of the carbons. Chemically reduced ones include IMIDAZOLINES and IMIDAZOLIDINES. Distinguish from 1,2-diazole (PYRAZOLES).