What it is
Atrial natriuretic peptide is a 28-amino-acid hormone made by the heart. Its sequence is SLRRSSCFGGRMDRIGAQSGLGCNSFRY, with a disulfide bond between the cysteines at positions 7 and 23 that closes a 17-residue ring — the shape every natriuretic peptide shares (UniProt P01160). "Natriuretic" means it makes the body excrete sodium (natrium); "atrial" names where it is made, the heart's two upper chambers.
ANP is cut from a 151-residue precursor encoded by the NPPA gene. That precursor yields more than one active piece, and UniProt lists them separately:
| Fragment | Residues of the precursor | Length |
|---|---|---|
| Long-acting natriuretic peptide | 26–55 | 30 |
| Vessel dilator | 56–92 | 37 |
| Kaliuretic peptide | 104–123 | 20 |
| Urodilatin (made in the kidney) | 120–151 | 32 |
| ANP | 124–151 | 28 |
Lengths are our count from UniProt's positions. At 28 residues ANP is well under the 40-residue line that separates peptides from proteins in US regulation (see peptide vs protein).
How it works
When extra blood volume stretches the atria, ANP is released into the blood. It binds natriuretic peptide receptor A (NPR1), which produces the messenger cGMP. UniProt summarises the result as vasodilation, natriuresis, diuresis and reduced aldosterone synthesis: vessels relax, the kidneys shed salt and water, and the adrenal glands make less of the hormone that holds salt in. Volume and pressure fall, and the stretch signal fades.
The discovery is one of physiology's clearest firsts. In 1981, de Bold and colleagues injected an extract of rat atrial muscle into rats and recorded "a rapid and potent natriuretic response" (Life Sci 28:89–94). It was the evidence that the heart is also an endocrine gland. That founding result is animal evidence; human physiology has since been studied in infusion experiments, and the evidence rows keep the two apart.
The drug: carperitide
No ANP drug is approved in the United States — a search of the FDA's Drugs@FDA dataset for carperitide returns no record (openFDA, 2026-10-17). Carperitide, described as "an α-human A-type natriuretic peptide", is given intravenously for acute heart failure, "primarily in Japan". A 2025 meta-analysis (Shiga et al., BMC Cardiovasc Disord) pooled nine studies:
| Analysis | In-hospital mortality, carperitide vs none |
|---|---|
| 4 RCTs + 5 propensity-matched studies | OR 1.38 (95% CI 1.07–1.78) — higher with carperitide |
| 4 RCTs alone | OR 0.85 (95% CI 0.07–10.49) — no significant difference |
Long-term mortality and heart-failure rehospitalisation showed no significant differences, and the authors conclude that carperitide's "clinical effectiveness has not been established." The pooled observational result points the wrong way, while the randomised trials are too few and too small to settle it — the confidence interval runs from a large benefit to a tenfold harm. The decision to use it belongs to the treating cardiology team.
ANP is not sold or studied as a wellness, weight-loss or performance peptide; no human trial for any such use was found, and the library records that absence rather than filling it.
Where it stands
- United States: no approved product containing ANP or carperitide. The natriuretic-peptide drug the FDA approved was nesiritide (Natrecor, NDA 020920, approved 2001-08-10), a copy of BNP now listed as Discontinued — with an FDA determination that it was not withdrawn for safety or effectiveness reasons (Drugs@FDA, data 2026-10-16). BNP itself is covered in the library's BNP and NT-proBNP entry.
- Japan: carperitide in hospital use for acute heart failure.
- Research record: PubMed indexes 11,526 records for "atrial natriuretic peptide", 558 tagged as randomised controlled trials; carperitide 352 and 27; ClinicalTrials.gov lists 45 studies naming ANP as an intervention (2026-10-17).
Related reading
ANP's ventricular sibling, and the one used as a blood test, is BNP and NT-proBNP; the third family member is the growth-plate peptide CNP, whose drug copy is vosoritide. ANP pushes against the pressure-raising hormones angiotensin and vasopressin.