Question

Which one of the following is not a second messenger in hormone action?
A. cGMP
B. Calcium
C. Sodium
D. cAMP

Answer 1

The control and coordination in the body is carried out by a group of chemicals known as hormones. These are the secretions of endocrine glands that are located at different parts of the body.

Complete answer:
The second messengers are the molecules, which bring about the changes in the cell upon the action of various hormones. These molecules are required for hormones that cannot directly permeate and act on the cell nucleus, such as many water-soluble hormones. Sodium does not act as a second messenger for any hormone.
Considering the other given options:
-c GMP is also known as cyclic guanosine monophosphate. It acts as a second messenger by the mechanism of activation of protein kinases present within the cell. It is mainly required for peptide hormones which are impermeable to the cells. Thus, it is not an appropriate answer.
-Calcium functions as a second messenger in the phosphor-inositol pathway. It is required for several hormones such as GnRH, oxytocin, and TRH. Thus it is not the appropriate answer.
-cAMP functions as a secondary messenger for several hormones such as Calcitonin, Glucagon, and TSH. Thus it is not an appropriate answer.
Therefore from the above-given options, the most appropriate one is C, that is Sodium does not act as a second messenger in hormone action.

Note: The secondary messengers are of three different types. They are hydrophobic messengers which are molecules that are insoluble in water such as diacylglycerol. The next group is the hydrophilic messenger, which is water-soluble and is located within the cytoplasm, such as cAMP. The last group is the gaseous messengers including nitric oxide and carbon monoxide.