cANF causes endothelial cell hyperpolarization by activation of chloride channels

Aaron Simon, Gong Xin Liu, Gideon Koren, Gaurav Choudhary

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Objectives: Natriuretic peptides bind with natriuretic peptide receptor (NPR)-C, which can alter cellular function through its interaction with the Gi protein complex. NPR-C has been found to mediate the activation of K+ channels and non-selective cation channels in vascular smooth muscle and cardiac fibroblast cells, respectively. However, the electrophysiological effect of NPR-C activation on endothelial cells (EC) has not been previously examined. In this study we sought to elucidate the effect of cANF(4-23), a selective NPR-C ligand, on EC membrane potential (Em). Methods/results: Changes in EC Em was measured through non-invasive fluorescence imaging. EC were preincubated in the potentiometric dye, DiBAC4(3) and subsequently exposed to cANF(4-23), in the presence of selective inhibitors of ion-channels or second messengers. NPR-C expression in rat lung microvascular endothelial cells was assessed by RT-PCR. cANF(4-23) induced a sustained decrease in EC cellular fluorescence, indicating endothelial cell hyperpolarization. The cANF-induced hyperpolarization could not be attenuated by TEA, barium, ouabain or by the reduction of extracellular Ca2+. Further, the cANF-induced hyperpolarization was insensitive to inhibition of Gi and protein kinase G (PKG), downstream messengers of NPRs. However, the Cl- channel inhibitors, 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid, niflumic acid, and hypertonic saline attenuated the cANF-induced hyperpolarization. Perforated patch clamp recordings confirmed the cANF-induced current was carried by Cl- and could be inhibited by niflumic acid. RT-PCR confirmed expression of NPR-C in vascular smooth muscle cells but not in EC. Conclusions: cANF causes hyperpolarization that is most likely mediated via activation of Cl- channels by a PKG and Gi independent mechanism.

Original languageEnglish
Pages (from-to)2337-2342
Number of pages6
Issue number12
StatePublished - Dec 2009
Externally publishedYes


  • Endothelial cell
  • Ion channel
  • Membrane potential
  • Natriuretic peptide
  • Natriuretic peptide receptor-C


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