Which of the following is most likely to cause an increase in the glomerular filtration rate?

Options

A. Volume depletion
B. Blockage of ureter
C. Dilation of the afferent arterioles
D. Release of Aldosterone from pituitary

Answer

To determine which of the following options is most likely to cause an increase in the glomerular filtration rate (GFR), we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Glomerular Filtration Rate (GFR)**:
- GFR is the rate at which blood is filtered in the kidneys. It is influenced by the pressure gradient across the glomerular capillaries.

2. **Analyzing the Options**:
- **Option A: Volume Repletion**:
- Volume repletion refers to increasing the volume of blood. This typically increases blood pressure, which can enhance GFR. However, if the volume is depleted (not repleted), it would decrease GFR. Therefore, this option is not likely to cause an increase in GFR.

- **Option B: Blockage of Ureters**:
- A blockage in the ureters would prevent urine from flowing from the kidneys to the bladder. This would lead to an increase in pressure in the renal pelvis, which could decrease GFR. Thus, this option is also not likely to increase GFR.

- **Option C: Dilation of Efferent Arterioles**:
- Dilation of the efferent arterioles decreases resistance in the outflow of blood from the glomeruli. This can lead to an increase in hydrostatic pressure within the glomeruli, resulting in an increased GFR. Therefore, this option is likely to cause an increase in GFR.

- **Option D: Release of Aldosterone from Pituitary**:
- Aldosterone primarily regulates sodium and water balance, but its release generally leads to increased blood volume and pressure. However, it is not directly linked to an increase in GFR and can sometimes lead to a decrease in GFR due to vasoconstriction effects. Thus, this option is not likely to increase GFR.

3. **Conclusion**:
- After analyzing all the options, the most likely cause of an increase in the glomerular filtration rate is **Option C: Dilation of Efferent Arterioles**.

### Final Answer:
**Option C: Dilation of Efferent Arterioles**

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