N-Arachidonoyl glycine suppresses Na⁺/Ca²⁺ exchanger-mediated Ca²⁺ entry into endothelial cells and activates BK(Ca) channels independently of GPCRs. Br J Pharmacol 2013 Jun;169(4):933-48
Date
03/23/2013Pubmed ID
23517055Pubmed Central ID
PMC3687672DOI
10.1111/bph.12180Scopus ID
2-s2.0-84878338494 (requires institutional sign-in at Scopus site) 23 CitationsAbstract
BACKGROUND AND PURPOSE: N-Arachidonoyl glycine (NAGly) is a lipoamino acid with vasorelaxant properties. We aimed to explore the mechanisms of NAGly's action on unstimulated and agonist-stimulated endothelial cells.
EXPERIMENTAL APPROACH: The effects of NAGly on endothelial electrical signalling were studied in combination with vascular reactivity.
KEY RESULTS: In EA.hy926 cells, the sustained hyperpolarization to histamine was inhibited by the non-selective Na⁺/Ca²⁺ exchanger (NCX) inhibitor bepridil and by an inhibitor of reversed mode NCX, KB-R7943. In cells dialysed with Cs⁺-based Na⁺-containing solution, the outwardly rectifying current with typical characteristics of NCX was augmented following histamine exposure, further increased upon external Na⁺ withdrawal and inhibited by bepridil. NAGly (0.3-30 μM) suppressed NCX currents in a URB597- and guanosine 5'-O-(2-thiodiphosphate) (GDPβS)-insensitive manner, [Ca²⁺]i elevation evoked by Na⁺ removal and the hyperpolarization to histamine. In rat aorta, NAGly opposed the endothelial hyperpolarization and relaxation response to ACh. In unstimulated EA.hy926 cells, NAGly potentiated the whole-cell current attributable to large-conductance Ca²⁺-activated K⁺ (BK(Ca)) channels in a GDPβS-insensitive, paxilline-sensitive manner and produced a sustained hyperpolarization. In cell-free inside-out patches, NAGly stimulated single BK(Ca) channel activity.
CONCLUSION AND IMPLICATIONS: Our data showed that NCX is a Ca²⁺ entry pathway in endothelial cells and that NAGly is a potent G-protein-independent modulator of endothelial electrical signalling and has a dual effect on endothelial electrical responses. In agonist pre-stimulated cells, NAGly opposes hyperpolarization and relaxation via inhibition of NCX-mediated Ca²⁺ entry, while in unstimulated cells, it promotes hyperpolarization via receptor-independent activation of BK(Ca) channels.
Author List
Bondarenko AI, Drachuk K, Panasiuk O, Sagach V, Deak AT, Malli R, Graier WFAuthor
Kostiantyn Drachuk Postdoctoral Fellow in the Medicine department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnimalsAorta
Arachidonic Acids
Calcium Channel Blockers
Calcium Signaling
Cell Line
Cell Membrane
Cell-Free System
Endothelium, Vascular
Glycine
Histamine
Human Umbilical Vein Endothelial Cells
Humans
In Vitro Techniques
Large-Conductance Calcium-Activated Potassium Channels
Male
Membrane Potentials
Muscle, Smooth, Vascular
Rats
Rats, Wistar
Receptors, G-Protein-Coupled
Sodium-Calcium Exchanger
Vasoconstriction
Vasodilator Agents
