Question
Which one of the following is not a second messenger in hormone action?
-
cGMP
-
Calcium
-
Sodium
-
cAMP
Solution
C.
Sodium
Second messengers are the organic molecules and sometimes the metal ions, acting as intracellular signals, whose production or release usually amplifies a signal such as a hormone, received at the cell surface.
Sodium (Na) is not a second messenger to be discovered.
In addition to cyclic AMP, Cyclic Guanosine Monophosphate (CGMP) functions as a second messenger in certain cases.
Calcium ions (Ca++) also act as second messenger in phospholipase 
second messenger system.
