Figure 2.

Schematic representation of the difference between nNOS and iNOS in the corporal smooth muscle cell. nNOS is involved in the neurogenic stimulation of nitric oxide (NO) within the nerve terminals. This neurally derived NO rapidly traverses from the nerve terminal into the cytoplasm of the underlying smooth muscle cell to activate guanylyl cyclase to form cGMP from GTP and induce smooth muscle relaxation (the erectile state). cGMP is endogenously degraded by PDE into 5’-GMP. iNOS originates from the smooth muscle cell itself and the NO from iNOS combats the oxidative stress that is ongoing within the mitochondria (M).