Fig. 6.

Suppression of SNAP-induced cGMP formation by proinflammatory cytokines via iNOS- and NF-κB–mediated PDE1A activity. Longitudinal muscle cells were isolated from muscle strips cultured in the presence of IL-1β (10 ng/ml) or TNF-α (1 nM) for 48 hours. In some experiments, muscle strips were cultured with IL-1β (10 ng/ml) or TNF-α (1 nM) in the presence of NF-κB inhibitor MG132 (10 µM), iNOS inhibitor 1400W (10 µM), PDE1 inhibitor vinpocetine (50 µM), or 1400W in combination with MG132 or vinpocetine for 48 hours. cGMP levels in response to SNAP (10 µM) were measured in the absence of IBMX by radioimmunoassay. Values are the means ± S.E.M. of five experiments. **P < 0.01, significant inhibition compared with control SNAP-induced cGMP formation (solid bar).