Identification of cytosolic phosphodiesterases in the erythrocyte: a possible role for PDE5.

Background: Within erythrocytes (RBCs), cAMP levels are regulated by phosphodiesterases (PDEs). Increases in cAMP and ATP release associated with activation of β-adrenergic receptors (βARs) and prostacyclin receptors (IPRs) are regulated by PDEs 2, 4 and PDE 3, respectively. Here we establish the presence of cytosolic PDEs in RBCs and determine a role for PDE5 in regulating levels of cGMP.