Brain natriuretic peptide is degraded by-
**Core Concept**
Brain natriuretic peptide (BNP) is a hormone released by the heart's ventricles in response to increased stretch and pressure, playing a crucial role in regulating blood pressure and fluid balance. The degradation of BNP is essential for its short half-life and precise physiological function.
**Why the Correct Answer is Right**
BNP is primarily degraded by neutral endopeptidase (NEP), also known as neprilysin, which breaks down the peptide at various sites, leading to its inactivation. This process is essential for maintaining the delicate balance of BNP levels in the circulation.
**Why Each Wrong Option is Incorrect**
**Option A:** Angiotensin-converting enzyme (ACE) is not directly involved in BNP degradation, although it plays a crucial role in the renin-angiotensin-aldosterone system (RAAS), which is closely linked to BNP function.
**Option B:** Aminopeptidases are involved in the degradation of various peptides, but they are not the primary enzymes responsible for BNP breakdown.
**Option C:** Endothelin-converting enzyme (ECE) is involved in the conversion of big endothelin-1 to endothelin-1, and is not directly related to BNP degradation.
**Option D:** There is no significant evidence to suggest that BNP is degraded by carboxypeptidase.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that BNP levels can be elevated in conditions such as heart failure, pulmonary embolism, and pericardial effusion, making it a useful biomarker for diagnosing and monitoring these conditions.
**Correct Answer:** C.