10.03.4 Nitric Oxide and Erectile Dysfunction

On the smooth muscle of the corpus carvenosum (penile smooth muscle) endogenous nitric oxide both as a neurotransmitter and local chemical mediator stimulated guanylate cyclase to promote the conversion of GTP to cGMP.  The cGMP relaxes the corpus carvenosum to produce a penile erection.  The rapid breakdown of cGMP by phosphodiesterase V ends the relaxation and the erection.  Sildenafil inhibits phosphodiesterase V to increase and prolong the effects of cGMP, with increased relaxation of the corpus carvenosum and increased penile erection (Figure 10.10).

Figure 10.10 Mechanism of action of sildenafil (Copyright QUT, Sheila Doggrell)
Pharmacology InOneSemester,
Mar 24, 2015, 9:03 PM