Consider the Phototransduction Cascade

Multiple Choice

Consider the phototransduction cascade. Viagra (sildenafil) is a drug that inhibits phosphodiesterases. What might you expect would be a side effect of Viagra related to visual function?

A) Impaired ability of rhodopsin to detect photons
B) Impaired ability to degrade cGMP, thus limiting the cell's ability to hyperpolarize in response to light
C) Impaired ability for transducing to exchange GDP for GTP and thus activate second messengers
D) all of the above