HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplemental Figures All Versions of this Article: 296/2/L248    most recent 90303.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Simon, A. Articles by Choudhary, G. Search for Related Content PubMed PubMed Citation Articles by Simon, A. Articles by Choudhary, G.

Mechanism of C-type natriuretic peptide-induced endothelial cell hyperpolarization

¹Vascular Research Laboratory, Providence VA Medical Center, and ²Department of Medicine, Warren Alpert Medical School of Brown University, Providence, Rhode Island

Submitted 7 May 2008 ; accepted in final form 25 November 2008

C-type natriuretic peptide (CNP) has a demonstrated hyperpolarizing effect on vascular smooth muscle cells. However, its autocrine function, including its electrophysiological effect on endothelial cells, is not known. Here, we report the effect of CNP on the membrane potential (E_m) of pulmonary microvascular endothelial cells and describe its target receptors, second messengers, and ion channels. We measured changes in E_m using fluorescence imaging and perforated patch-clamping techniques. In imaging experiments, samples were preincubated in the potentiometric dye DiBAC₄(3), and subsequently exposed to CNP in the presence of selective inhibitors of ion channels or second messengers. CNP exposure induced a dose-dependent decrease in fluorescence, indicating that CNP induces endothelial cell hyperpolarization. CNP-induced hyperpolarization was inhibited by the K⁺ channel blockers, tetraethylammonium or iberiotoxin, the nonspecific cation channel blocker, La³⁺, or by depletion or repletion of extracellular Ca²⁺ or K⁺, respectively. CNP-induced hyperpolarization was also blocked by pharmacological inhibition of PKG or by small interfering RNA (siRNA)-mediated knockdown of natriuretic peptide receptor-B (NPR-B). CNP-induced hyperpolarization was mimicked by the PKG agonist, 8-bromo-cGMP, and attenuated by both the endothelial nitric oxide synthase (eNOS) inhibitor, N-nitro-L-arginine methyl ester (L-NAME), and the soluble guanylyl cyclase (sGC) inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. Presence of iberiotoxin-sensitive, CNP-induced outward current was confirmed by perforated patch-clamping experiments. We conclude that CNP hyperpolarizes pulmonary microvascular endothelial cells by activating large-conductance calcium-activated potassium channels mediated by the activation of NPR-B, PKG, eNOS, and sGC.

large-conductance calcium-activated potassium channels; ion channel

This article has been cited by other articles:

				S. L. Sandow and T. H. Grayson Limits of isolation and culture: intact vascular endothelium and BKCa Am J Physiol Heart Circ Physiol, July 1, 2009; 297(1): H1 - H7. [Abstract] [Full Text] [PDF]