BNP is degraded by:
**Core Concept:**
B-type natriuretic peptide (BNP) is a peptide hormone produced by the ventricles of the heart in response to ventricular wall stretching, typically due to heart failure, hypertension, or myocardial infarction. It plays a crucial role in regulating fluid balance and blood pressure. The correct degradation pathways for BNP involve enzymes.
**Why the Correct Answer is Right:**
BNP is degraded primarily by two enzymes: neprilysin (NEP) and carboxypeptidase M (CPM). These enzymes act on the C-terminal end of BNP, cleaving off specific amino acids to reduce its bioactivity. Inhibition of neprilysin leads to increased BNP levels, which can be exploited therapeutically.
**Why Each Wrong Option is Incorrect:**
A) Option A (Angiotensin-Converting Enzyme, ACE) is incorrect because ACE primarily degrades angiotensin I and angiotensin II, not BNP.
B) Option B (Angiotensin-Converting Enzyme, ACE) is incorrect as mentioned above.
C) Option C (Angiotensin-Converting Enzyme, ACE) is incorrect as explained previously.
D) Option D (Neprilysin, NEP) is incorrect, as neprilysin is responsible for the correct degradation of BNP.
**Clinical Pearl:**
Understanding the role of neprilysin in the degradation of BNP can be valuable for making clinical decisions regarding treatment options in patients with heart failure. Inhibition of neprilysin, such as with drugs like sacubitril/valsartan (Entresto), can lead to increased BNP levels, which can be used as a biomarker for heart failure diagnosis, prognosis, and response to therapy.