Nitric oxide effects are downstream from cAMP which is degraded by PDE4. cAMP increases usually come from g-protein coupled receptors releasing it and then ther

Nitric oxide effects are downstream from cAMP which is degraded by PDE4. cAMP increases usually come from g-protein coupled receptors releasing it and then there's a cascade that depending on the cell type may create Nitric oxide. However, nitric oxide is upstream of cGMP metabolically and is degraded by PDE5. https://www.reading.ac.uk/nitricoxide/intro/no/cgmp.htm https://www.reading.ac.uk/nitricoxide/intro/no/cgmp.htm