Figure 7.

Effects of montelukast (0.5–20 µmol·L⁻¹), rolipram (20 µmol·L⁻¹) and 3-isobutyl-1-methylxanthine (50 µmol·L⁻¹) on cAMP (upper graph) and cGMP (lower graph) phosphodiesterase (PDE) activities in neutrophil cytosol. The results of four to eight and two to four experiments for cAMP and cGMP PDE activity respectively are presented as the mean percentages of the drug-free control systems and vertical lines show SEM. In the case of the cAMP/PDE experiments, the absolute values for the cytosol-free background system and for the cytosol-containing systems in the absence of the drugs were 1213 ± 53 and 14 525 ± 232 counts per minute respectively. The corresponding values for the cGMP/PDE experiments were 2031 ± 206 and 21 381 ± 501 counts per minute. *P < 0.05 for comparison with the corresponding drug-free control system.