G protein-dependent activation of smooth muscle eNOS via natriuretic peptide clearance receptor

Am J Physiol. 1998 Dec;275(6):C1409-16. doi: 10.1152/ajpcell.1998.275.6.C1409.


In gastrointestinal smooth muscle, the neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) induce relaxation by interacting with VIP2/PACAP3 receptors coupled via Gs to adenylyl cyclase and with distinct receptors coupled via Gi1 and/or Gi2 to a smooth muscle endothelial nitric oxide synthase (eNOS). The present study identifies the receptor as the single-transmembrane natriuretic peptide clearance receptor (NPR-C). RT-PCR and Northern analysis demonstrated expression of the natriuretic peptide receptors NPR-C and NPR-B but not NPR-A in rabbit gastric muscle cells. In binding studies using 125I-labeled atrial natriuretic peptide (125I-ANP) and 125I-VIP as radioligands, VIP, ANP, and the selective NPR-C ligand cANP(4-23) bound with high affinity to NPR-C. ANP, cANP-(4-23), and VIP initiated identical signaling cascades consisting of Ca2+ influx, activation of eNOS via Gi1 and Gi2, stimulation of cGMP formation, and muscle relaxation. NOS activity and cGMP formation were abolished (93 +/- 3 to 96 +/- 2% inhibition) by nifedipine, pertussis toxin, the NOS inhibitor, NG-nitro-L-arginine, and the antagonists ANP-(1-11) and VIP-(10-28). NOS activity stimulated by all three ligands in muscle membranes was additively inhibited by Gi1 and Gi2 antibodies (82 +/- 2 to 84 +/- 1%). In reconstitution studies, VIP, cANP-(4-23), and guanosine 5'-O-(3-thiotriphosphate) stimulated NOS activity in membranes of COS-1 cells cotransfected with NPR-C and eNOS. The results establish a unique mechanism for G protein-dependent activation of a constitutive NOS expressed in gastrointestinal smooth muscle involving interaction of the relaxant neuropeptides VIP and PACAP with a single-transmembrane natriuretic peptide receptor, NPR-C.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Atrial Natriuretic Factor / metabolism
  • Atrial Natriuretic Factor / pharmacology
  • COS Cells
  • Cattle
  • GTP-Binding Proteins / physiology*
  • Gastric Mucosa / metabolism
  • Guanylate Cyclase / physiology*
  • Muscle, Smooth / cytology
  • Muscle, Smooth / enzymology*
  • Peptide Fragments / pharmacology
  • Rabbits
  • Receptors, Atrial Natriuretic Factor / physiology*
  • Signal Transduction / physiology
  • Stomach / cytology
  • Vasoactive Intestinal Peptide / metabolism
  • Vasoactive Intestinal Peptide / physiology


  • Peptide Fragments
  • atrial natriuretic factor (4-23)NH2, de-Gln(18)-de-Ser(19)-de-Gly(20,22)-de-Leu(21)-
  • Vasoactive Intestinal Peptide
  • Atrial Natriuretic Factor
  • GTP-Binding Proteins
  • Guanylate Cyclase
  • Receptors, Atrial Natriuretic Factor
  • atrial natriuretic factor receptor B
  • atrial natriuretic factor receptor C