fig3

Figure 3. Characteristics of the cGMP/protein kinase G (PKG) pathway. Soluble guanylate cyclase (sGC) is activated by nitric oxide (NO) and by three drugs, namely Riociguate, YC-1, and Bay 41-2271, and is inhibited by ODQ. Activated sGC converts GTP to cGMP while phosphodiesterase 5 (PDE5) hydrolyzes cGMP to 5’GMP. PDE5 inhibitors include tadalafil (Cialis), sildenafil (Viagra) and vardenafil (Levitra). Elevated cGMP activates PKG, which affects many important targets