BRL 50481 is a potent, selective inhibitor of phosphodiesterase (PDE) 7, inhibiting human recombinant PDE7A1 with a Ki value of 180 nM. It is much less effective against PDE3 and PDE4 and is without effect against PDE1B, PDE1C, PDE2, and PDE5. Through its effects on PDE7A1, BRL 50481 enhances the inhibitory effects of the PDE4 blocker rolipram on monocytes, lung macrophages, and CD8+ T-lymphocytes. BRL 50481, at 30 μM, promotes apoptosis in chronic lymphocytic leukemia cells overexpressing PDE7B, suggesting that this compound also acts against PDE7B. BRL 50481 can be used to evaluate the role of PDE7 isoforms in intracellular signaling.
