Natriuretic Peptides Do Not Increase Systolic Blood Pressure
None of the natriuretic peptides—ANP, BNP, or CNP—increase systolic blood pressure; they all function as vasodilators and blood pressure-lowering hormones that antagonize the renin-angiotensin system. 1, 2
Physiological Actions of Natriuretic Peptides
ANP (Atrial Natriuretic Peptide)
- ANP is synthesized and secreted primarily from the cardiac atria in response to atrial stretch and volume expansion 3, 4
- ANP decreases blood pressure through multiple mechanisms: diuretic/natriuretic actions, direct vasodilation, and inhibition of aldosterone secretion 2
- ANP exhibits antagonistic effects against angiotensin II, the primary vasoconstrictor hormone 2
- In normal adults, ANP secretion occurs predominantly from the atria, with minimal ventricular contribution 3
BNP (B-Type Natriuretic Peptide)
- BNP is secreted mainly from the left ventricle in response to ventricular wall stress and pressure/volume overload 3, 4
- BNP shares the same blood pressure-lowering mechanisms as ANP: natriuresis, vasodilation, and aldosterone suppression 2
- BNP secretion increases proportionally with the severity of left ventricular dysfunction, serving as a compensatory mechanism to reduce cardiac afterload 3
- In heart failure, both ANP and BNP expression are augmented in ventricular myocardium as a cardiac compensatory response 5
CNP (C-Type Natriuretic Peptide)
- CNP is primarily a neuropeptide synthesized in the brain, vasculature, and central nervous system—not a cardiac hormone 4, 2
- CNP regulates vascular tone and blood pressure through local paracrine mechanisms, promoting vasodilation rather than vasoconstriction 2
- CNP is not expressed at significant levels in normal adult myocardium 5
- CNP primarily stimulates long bone growth and serves vascular regulatory functions 6
Clinical Implications
Diagnostic Use
- Elevated BNP and NT-proBNP levels indicate increased ventricular wall stress from pressure or volume overload, not hypertension 1
- BNP levels >100 pg/mL or NT-proBNP >300 pg/mL suggest heart failure and warrant echocardiographic evaluation 1
- BNP production is affected by both systolic and diastolic ventricular load, making it a sensitive marker of cardiac dysfunction 1
Therapeutic Applications
- Synthetic natriuretic peptide analogs (nesiritide, carperitide) are used to lower blood pressure and reduce cardiac afterload in acute decompensated heart failure—the opposite of increasing systolic pressure 6
- These agents work by enhancing the natural vasodilatory and natriuretic effects of endogenous natriuretic peptides 6
Common Pitfall to Avoid
Do not confuse elevated natriuretic peptide levels with hypertension. Elevated BNP/ANP levels in hypertensive patients reflect the cardiac response to increased afterload (ventricular wall stress), not a cause of elevated blood pressure 1. The natriuretic peptide system represents a compensatory mechanism attempting to counteract elevated blood pressure through vasodilation and sodium excretion 2.