Release of C-type natriuretic peptide accounts for the biological activity of endothelium-derived hyperpolarizing factor

doi:10.1073/pnas.0336365100

Release of C-type natriuretic peptide accounts for the biological activity of endothelium-derived hyperpolarizing factor

^*Department of Clinical Pharmacology, St. Bart's and Royal London School of Medicine, Charterhouse Square, London EC1M 6BQ, United Kingdom; ^†Department of Physiology, University of Aarhus, Universitetsparken 160, DK8000 Aarhus C, Denmark; and ^‡Wolfson Institute for Biomedical Research, University College London, Cruciform Building, Gower Street, London WC1E 6AE, United Kingdom

Edited by Louis J. Ignarro, University of California School of Medicine, Los Angeles, CA, and approved December 10, 2002 (received for review October 21, 2002)

Abstract

Endothelial cells in most vascular beds release a factor that hyperpolarizes the underlying smooth muscle, produces vasodilatation, and plays a fundamental role in the regulation of local blood flow and systemic blood pressure. The identity of this endothelium-derived hyperpolarizing factor (EDHF), which is neither NO nor prostacyclin, remains obscure. Herein, we demonstrate that in mesenteric resistance arteries, release of C-type natriuretic peptide (CNP) accounts for the biological activity of EDHF. Both produce identical smooth muscle hyperpolarizations that are attenuated in the presence of high [K⁺], the G_i G protein (G_i) inhibitor pertussis toxin, the G protein-gated inwardly rectifying K⁺ channel inhibitor tertiapin, and a combination of Ba²⁺ (inwardly rectifying K⁺ channel blocker) plus ouabain (Na⁺/K⁺-ATPase inhibitor). Responses to EDHF and CNP are unaffected by the natriuretic peptide receptor (NPR)-A/B antagonist HS-142-1, but mimicked by the selective NPR-C agonist, cANF^4–23. EDHF-dependent relaxation is concomitant with liberation of endothelial CNP; in the presence of the myoendothelial gap-junction inhibitor 18α-glycyrrhetinic acid or after endothelial denudation, CNP release and EDHF responses are profoundly suppressed. These data demonstrate that acetylcholine-evoked release of endothelial CNP activates NPR-C on vascular smooth muscle that via a G_i coupling promotes Ba²⁺/ouabain-sensitive hyperpolarization. Thus, we have revealed the identity of EDHF and established a pivotal role for endothelial-derived CNP in the regulation of vascular tone and blood flow.

Footnotes

↵ § To whom correspondence should be addressed. E-mail: a.hobbs{at}ucl.ac.uk.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations:

CNP,

C-type natriuretic peptide;

EDHF,

endothelium-derived hyperpolarizing factor;

GIRK,

G protein-gated inwardly rectifying K+ channel;

NPR,

natriuretic peptide receptor;

ACh,

acetylcholine;

CTx,

charybdotoxin;

PTx,

pertussis toxin;

l-NAME,

NG-nitro-l-arginine methyl ester;

18α-GA,

18α-glycyrrhetinic acid;

PGI2,

prostacyclin;

Gi,

Gi G protein