Figure 1.

PDE1–5 isoenzyme activities in human lung macrophages and LPS-induced up-regulation of PDE4. Lung macrophages (purity > 95%) were homogenized, and PDE activities assessed in whole lysates at 0.5 µM cAMP or cGMP substrate concentrations. (A) Enzymatic activities reflecting basal cAMP and cGMP hydrolyses and PDE1–5 are shown. PDE1 activities are depicted as cGMP or cAMP hydrolysis stimulated by Ca⁺⁺–calmodulin. (B) Lung macrophages were incubated with 10 ng·mL⁻¹ LPS over 24 h. Enzymic activities reflecting basal cAMP and cGMP hydrolysis as well as PDE4 are depicted. Results from four different donors are shown as the means ± SEM. *P < 0.05, significantly different from control.