Phosphodiesterases (PDEs) metabolize cyclic nucleotides limiting the effects of vasodilators such as prostacyclin and nitric oxide (NO). In this study, DNA microarray techniques were used to assess the impact of NO on the expression of PDE genes in pulmonary arterial smooth muscle cells (rPaSMC). Incubation of rPaSMC with S-nitroso-L-glutathione (GSNO) increased expression of a PDE isoform that specifically metabolizes cAMP (PDE4B) in a dose- and time-dependent manner. GSNO increased PDE4B protein levels, and rolipram-inhibitable PDE activity was 2.3±1.0-fold greater in GSNO-treated rPaSMC than in untreated cells. The soluble guanylate cyclase (sGC) inhibitor, ODQ, and the cAMP-dependent protein kinase (PKA) inhibitor, H89, prevented the induction of PDE4B gene expression by GSNO, but the protein kinase G (PKG) inhibitors, Rp-8-pCPT-cGMPs and KT5823, did not. Incubation of rPaSMC with interleukin-1 and tumor necrosis factor- induced PDE4B gene expression, an effect which was inhibited by L-NIL, an antagonist of NO synthase 2. The GSNO-induced increase in PDE4B mRNA levels was blocked by actinomycin D but augmented by cycloheximide. Infection of rPaSMC with an adenovirus specifying a dominant-negative CREB mutant inhibited the GSNO-induced increase of PDE4B gene expression. These results suggest that exposure of rPaSMC to NO induces expression of PDE4B via a mechanism that requires cGMP synthesis by sGC but not PKG. The GSNO-induced increase of PDE4B gene expression is CREB-dependent. These findings demonstrate that NO increases expression of a cAMP-specific PDE and provide evidence for a novel [[rad]]cross-talk[[rad]] mechanism between cGMP and cAMP signalling pathways.