Which hormone reduces blood pressure by promoting natriuresis?

Which hormone reduces blood pressure by promoting natriuresis?

• A. Atrial natriuretic peptide
• B. Angiotensin II
• C. Epinephrine
• D. Vasopressin

Answer: (A)

Natriuresis and how hormones regulate blood pressure through sodium balance is being tested. Natriuresis is the excretion of sodium in urine, and the heart can signal the kidneys to get rid of more sodium when blood volume is high. Atrial natriuretic peptide is released from atrial muscle cells in response to stretch from increased blood volume. It lowers blood pressure mainly by promoting natriuresis: it acts on the kidneys to excrete more sodium and water, which reduces circulating volume. Mechanistically, it increases glomerular filtration and reduces Na+ reabsorption in the collecting ducts (in part by inhibiting ENaC and the Na+/K+-ATPase) and it suppresses renin and aldosterone, further decreasing Na+ reabsorption. The net effect is less volume and lower pressure. In contrast, angiotensin II raises blood pressure by causing vasoconstriction and increasing sodium reabsorption; epinephrine boosts blood pressure through sympathetic effects; vasopressin mainly promotes water reabsorption with less direct natriuresis, so it doesn’t drive sodium loss to lower pressure. Therefore, the hormone that reduces blood pressure by promoting natriuresis is atrial natriuretic peptide.

Natriuresis and how hormones regulate blood pressure through sodium balance is being tested. Natriuresis is the excretion of sodium in urine, and the heart can signal the kidneys to get rid of more sodium when blood volume is high. Atrial natriuretic peptide is released from atrial muscle cells in response to stretch from increased blood volume. It lowers blood pressure mainly by promoting natriuresis: it acts on the kidneys to excrete more sodium and water, which reduces circulating volume. Mechanistically, it increases glomerular filtration and reduces Na+ reabsorption in the collecting ducts (in part by inhibiting ENaC and the Na+/K+-ATPase) and it suppresses renin and aldosterone, further decreasing Na+ reabsorption. The net effect is less volume and lower pressure.

In contrast, angiotensin II raises blood pressure by causing vasoconstriction and increasing sodium reabsorption; epinephrine boosts blood pressure through sympathetic effects; vasopressin mainly promotes water reabsorption with less direct natriuresis, so it doesn’t drive sodium loss to lower pressure. Therefore, the hormone that reduces blood pressure by promoting natriuresis is atrial natriuretic peptide.