Nitric Oxide (NO2) is controlled by PDE5, an enzyme which degrades the effect of NO2. The are NO suppliments that can increase nitric oxide in your body, but you can effectively block PDE5. How? Cialis, viagra, levitra. I wouldnt make a habit of using these drugs for NO2 pumps, but pop 25mg of cialis before a good weekend (and workout) and tell me if you dont experience some rediculous pumps.