Which of the following hormones stimulates by juxtaglomerular cells of the kidney in response to hypoxia?

Options

A. Calcitrol
B. Renin
C. Erythropoietin
D. All of these

Answer

To solve the question regarding which hormone is stimulated by juxtaglomerular cells of the kidney in response to hypoxia, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks which hormone is stimulated by the juxtaglomerular cells of the kidney when there is a lack of oxygen (hypoxia).

2. **Identifying the Juxtaglomerular Cells**: Juxtaglomerular (JG) cells are specialized cells located in the kidney, specifically in the juxtaglomerular apparatus. They play a critical role in regulating blood pressure and the filtration rate of the glomerulus.

3. **Analyzing the Options**:
- **Option 1: Calcitriol**: This hormone is involved in calcium metabolism and is produced in the kidneys, but it is not stimulated by hypoxia. Therefore, this option is incorrect.
- **Option 2: Renin**: Renin is released by the juxtaglomerular cells in response to low sodium levels or low blood pressure, not specifically in response to hypoxia. Thus, this option is also incorrect.
- **Option 3: Erythropoietin (EPO)**: Erythropoietin is a hormone that stimulates the production of red blood cells and is indeed released by the juxtaglomerular cells in response to hypoxia. This is the correct answer.
- **Option 4: (Another hormone not specified)**: Since the question does not provide another option, we can conclude that this option is incorrect as well.

4. **Conclusion**: Based on the analysis, the hormone that is stimulated by juxtaglomerular cells of the kidney in response to hypoxia is **Erythropoietin (EPO)**.

### Final Answer:
**Erythropoietin (EPO)** is the hormone stimulated by juxtaglomerular cells of the kidney in response to hypoxia.