"Maty" wrote:
Gi Inhibitory through reduction of adenyl cyclase, cAMP and protein Kinase A. receptors are M2, alpha 2, D2.

Gs stimulatory through increase of adenyl cyclase, cAMP and protein Kinase A. receptors are Beta 1 and 2, D1, H2...

Gq stimulatory but totally different 2nd messenger DAG and IP3, action is to increase intracellular Ca2+ via stimulation of protein kinase C. Receptors are M1, alpha1, M3.

Histamine and Drug Nitrate act via Nitrite Oxide, guanylyl cyclase and cGMP. Final action is to dephosphorilate myosin so no contraction occurs.

There are also the ones that do not have 2nd messenger but are directly coupled to ions channels:
-Nicotinic receptors which activation opens Na/K channels same goes with Glutamic acid I think.
-GABAa , stimulation opens Cl- flux