AEMCA Practice Exam

Which substances are known to inhibit the release of ADH?

1. Renin and aldosterone

2. Aldosterone and cortisol

3. Atrial natriuretic peptide and cortisol

4. Angiotensin 1 and 2

The correct answer is: Atrial natriuretic peptide and cortisol

Atrial natriuretic peptide (ANP) is a key factor in inhibiting the release of antidiuretic hormone (ADH). ANP is produced by the heart in response to increased blood volume and pressure, promoting the excretion of sodium and water by the kidneys, which in turn decreases blood volume and pressure. This effect counteracts the action of ADH, which aims to retain water in the body. Cortisol, a stress hormone produced by the adrenal cortex, can also influence the body's fluid balance, but its primary role is in stress response and metabolism rather than directly inhibiting ADH. However, it has been observed that excessive cortisol levels may indirectly affect electrolyte balance and water retention, which can alter ADH function. The other substances listed, such as renin, aldosterone, angiotensin I, and angiotensin II, primarily play roles in promoting the retention of sodium and water, which would lead to an increase in blood volume and pressure, consequently stimulating rather than inhibiting the release of ADH. Therefore, the combination of ANP and the broader influence of cortisol on fluid balance makes the choice identifying these substances as the correct answer in the context of ADH regulation.