A drug inhibitor of cyclic GMP phosphodiestera... in rod photoreceptors?

Question

''The rod photoreptors in the eye are extremly sensitive to light. How would I expect the addition of a drug that is an inhibitor of Cyclic GMP photodiesterase and a drug that is a non-hydrolyzable analog of GTP to affect the light-sensing ability of the rod cells?

Answer 1

Hey I was going to reply and then you removed the question from biology !?! It was better to post it there.

if you have an inhibitor of cGMP phopshodiesterase then you will have no cGMP hydrolysis and thus the cation specific channels will remain open. Thus it would be impossible to generate a nerve signal (no hyperpolarization)

If you have a non hydrolyzable analogue of GTP then the cGMP phopshodiesterase will be always active (Ta-GTP will not be inactivated by hydrolysis to Ta-GDP) but also you can't form any cGMP. So you will endup with the channels always closed and you will have constant membrane hyperpolarizaion and signaling.



Edit: I've corrected the answer although it's better formulated in the "biology" section.Sorry...