Figure 5
Macrophages have a high endogenous PDE IV activity: VIP induction of cAMP is augmented by rolipram. Human monocytes (a) and monocyte-derived macrophages (b) were plated out at 5 × 105cells per well in a flat-bottomed 24-well plate and simultaneously treated with 10-6 M VIP, or VIP in the presence of 10 μM rolipram, and stimulated with 50 ng/ml PMA and 0.5 μg/ml ionomycin or 1 ng/ml LPS and incubated for 24 hours at 37°C in a 5% CO2 humidified atmosphere, after which time cell lysates were harvested and assayed for cAMP by immunoassay. Data are mean cAMP levels in pmol/ml of duplicate culture supernatants, showing a representative of n = 2 replicate experiments. Iono, ionomycin; LPS, lipopolysaccharide; PDE, phosphodiesterase; PMA, phorbol 12-myristate 13-acetate; Rol, rolipram; VIP, vasoactive intestinal peptide.