Question

yclic GMP, or cGMP, acts as a signaling molecule whose effects include relaxation of smooth muscle cells in artery walls. In the penis, this signaling pathway and the resulting dilation of blood vessels leads to an erection. Select the correct statement about the effect of Viagra on this signaling pathway.

A) Viagra increases the rate of hydrolysis of cGMP to GMP.
B) Viagra inhibits the hydrolysis of cGMP to GMP.
C) Viagra prevents the formation of cGMP.

Answer 1

Answer:

B) Viagra inhibits the hydrolysis of cGMP to GMP.

Explanation:

The mechanism of penis erection depends on the level of cGMP, the nitric oxide and the phosphodiesterase type 5 inhibitor (PDE5).

The production of Nitric oxide by the corpus cavernosum activates enzyme guanylyl cyclase which increases the level of the cGMP. The cGMP relaxes the muscles and increase the flow of the blood but as the signals from the brain come, the enzyme PDE 5 acts and converts the cGMP to GMP.

The viagra acts on the PDE5 and inhibits the enzyme thus inhibits the hydrolysis of the cGMP to GMP.

Thus, Option-B is the correct answer.