Which of the following does not favour the formation of large quantities of dilute urine

Options

A. Caffeine
B. Renin
C. Atrial-natriuretic factor
D. Alcohol

Answer

To determine which of the following does not favor the formation of large quantities of dilute urine, we will analyze each option provided:

1. **Caffeine**:
- Caffeine is known to act as a diuretic. It decreases water reabsorption in the nephrons, leading to the excretion of more water and thus the formation of dilute urine.
- Therefore, caffeine promotes the formation of dilute urine.

2. **Renin**:
- Renin is an enzyme secreted by the juxtaglomerular cells in the kidneys. It activates angiotensinogen, converting it into angiotensin I, which is then converted into angiotensin II.
- Angiotensin II promotes the reabsorption of water and sodium in the proximal convoluted tubule (PCT). This increased reabsorption leads to the formation of concentrated urine, not dilute urine.
- Thus, renin does not favor the formation of large quantities of dilute urine.

3. **Atrial Natriuretic Factor (ANF)**:
- ANF inhibits the secretion of renin. By inhibiting renin, it reduces water reabsorption, which promotes the formation of dilute urine.
- Therefore, ANF favors the formation of dilute urine.

4. **Alcohol**:
- Alcohol is a dehydrating agent and also acts as a diuretic. It leads to the excretion of large amounts of water, resulting in the formation of dilute urine.
- Hence, alcohol promotes the formation of dilute urine.

**Conclusion**: Among the options, **renin** is the correct answer as it does not favor the formation of large quantities of dilute urine.