Figure 5.

(a) Augmentation of PDE5 phosphorylation and activity by GSNO and ACh, and attenuation of these effects by the RhoA inhibitor C3 exoenzyme. (b) cGMP levels induced by PKC derived from RhoA activation in these experiments. Freshly dispersed gastric smooth muscle cells incubated with submaximal concentrations of GSNO (10 μM) and GSNO plus ACh in the presence or absence of PLC-β inhibitor U73122 (10 μM) or RhoA inhibitor C3 exoenzyme (2 μg ml⁻¹). PDE5 phosphorylation, PDE5 activity and cGMP levels were measured as described in the Methods section. PDE5 activity is expressed as c.p.m. per mg protein and cGMP levels as percentage increase above basal levels (0.36±0.05 pmol per mg protein). Values are means±s.e.mean of four experiments. ^**P<0.001 significant increase in PDE5 activity and decrease in cGMP levels in the presence of ACh compared with GSNO alone. GSNO, S-nitrosoglutathione.