Viagra, Cialis and other drugs known to alleviate 'erectile dysfunction' increase blood flow by:

Viagra, Cialis and other drugs known to alleviate 'erectile dysfunction' increase blood flow by:

Increasing the concentration of cyclic GMP in smooth muscle

Increasing phosphodiesterase (PDE-5) activity in smooth muscle

Increasing the concentration of the enzyme guanylate cyclase in smooth muscle

Increasing the concentration of cyclic GMP in smooth muscle is the correct answer. Viagra, Cialis, and similar drugs are phosphodiesterase type 5 (PDE-5) inhibitors. By inhibiting the action of PDE-5, these drugs prevent the breakdown of cyclic GMP, which is responsible for relaxing smooth muscle and increasing blood flow to the erectile tissue of the , thus helping to achieve and maintain an erection.