Which is not a secondary messenger in hormone mediated action?

Options

A. `IP_3`
B. `Ca^(2+)`
C. cAMP
D. `NaHCO_3`

Answer

To solve the question "Which is not a secondary messenger in hormone mediated action?", we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Secondary Messengers**:
- Secondary messengers are molecules that relay signals received at receptors on the cell surface to target molecules inside the cell. They play a crucial role in transmitting the effects of hormones and other signaling molecules.

2. **Analyzing Option 1: IP3 (Inositol 1,4,5-triphosphate)**:
- IP3 is known to be a secondary messenger involved in the signaling pathways of various hormones. It helps in the release of calcium ions from the endoplasmic reticulum.
- **Conclusion**: IP3 is a secondary messenger.

3. **Analyzing Option 2: Calcium**:
- Calcium ions (Ca²⁺) are widely recognized as secondary messengers in various signaling pathways. They are involved in processes such as muscle contraction and neurotransmitter release.
- **Conclusion**: Calcium is a secondary messenger.

4. **Analyzing Option 3: cAMP (Cyclic Adenosine Monophosphate)**:
- cAMP is another well-known secondary messenger that is involved in the signaling pathways of hormones like epinephrine and glucagon. It plays a significant role in propagating hormonal signals.
- **Conclusion**: cAMP is a secondary messenger.

5. **Analyzing Option 4: NaHCO3 (Sodium Bicarbonate)**:
- Sodium bicarbonate is not involved in hormone signaling as a secondary messenger. It is primarily known for its role in maintaining pH balance in the body and does not participate in the signaling pathways of hormones.
- **Conclusion**: NaHCO3 is not a secondary messenger.

### Final Answer:
The correct answer is **Option 4: NaHCO3**, as it does not act as a secondary messenger in hormone-mediated action.

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