Step I cAMP vs cGMP purposes??

[Daitong]

So can someone tell me the general rule of thumb for these two?


Obviously they activate PKA/PKG respectively, but is there a list of what the phosphorylation will do in certain parts of the body?

Like for example, FA will write ' Inhibition of phosphodiesterase III increases cAMP levels within platelets, which inhibits platelet aggregation andinduces vasodilation." like it's a well know fact that increased cAMP results in platelet aggregation and vasodil...


What rules of thumb do you guys go by for the purposes of these two messengers?

Thanks in advance!!

 

[Phloston]

So can someone tell me the general rule of thumb for these two?


Obviously they activate PKA/PKG respectively, but is there a list of what the phosphorylation will do in certain parts of the body?

Like for example, FA will write ' Inhibition of phosphodiesterase III increases cAMP levels within platelets, which inhibits platelet aggregation andinduces vasodilation." like it's a well know fact that increased cAMP results in platelet aggregation and vasodil...


What rules of thumb do you guys go by for the purposes of these two messengers?

Thanks in advance!!

Know the G-protein pathways cold.

Know cAMP, via adenylate cyclase, comes from ATP. And similarly cGMP, via guanylate cyclase, comes from GTP. Sounds ridiculously obvious, but it's tested and sometimes students think there's a trick there when there's not.

Sildenafil decreases the breakdown of cGMP. Nitrates increase the synthesis of cGMP. USMLE likes that.

Phototransduction involves cGMP, not cAMP.

Cilostazol is both an antiplatelet agent AND prevents the breakdown of cAMP (vasodilates). Dipyridamole is similar to cilostazol, but also works on cGMP in addition to cAMP.

Know both CFTR channel and insulin secretion are cAMP-mediated.

And tangentially, the CAMP test is used to identify Group B Strep (not the same as cAMP!!!; apparently CAMP comprises the names of the people who invented the test).

 

[worldbeater]

In addition to what my friend has said above, remember that cAMP produces sympathetic effects while cGMP produces parasympathetic effects.

Sildenafil decreases the breakdown of cGMP. Nitrates increase the synthesis of cGMP. USMLE likes that.

So with this nice explanation, you can see why both drugs work, they are increasing the levels of cGMP. They cause more parasympathetic effects, causing more blood flow to the penis and heart.