title: GPR55 agonist lysophosphatidylinositol and lysophosphatidylcholine inhibit endothelial cell hyperpolarization via GPR-independent suppression of Na+-Ca2+exchanger and endoplasmic reticulum Ca2+refilling.
abstract: Lysophosphatidylinositol (LPI) and lysophosphatidylcholine (LPC) are lipid signaling molecules that induce endothelium-dependent vasodilation. In addition, LPC suppresses acetylcholine (Ach)-induced responses. We aimed to determine the influence of LPC and LPI on hyperpolarizing responses in vitro and in situ endothelial cells (EC) and identify the underlying mechanisms. Using patch-clamp method, we show that LPI and LPC inhibit EC hyperpolarization to histamine and suppress Na+/Ca2+exchanged (NCX) currents in a concentration-dependent manner. The inhibition is non-mode-specific and unaffected by intracellular GDPβS infusion and tempol, a superoxide dismutase mimetic. In excised mouse aorta, LPI strongly inhibits the sustained and the peak endothelial hyperpolarization induced by Ach, but not by SKA-31, an opener of Ca2+-dependent K+channels of intermediate and small conductance. The hyperpolarizing responses to consecutive histamine applications are strongly reduced by NCX inhibition. In a Ca2+-re-addition protocol, bepridil, a NCX inhibitor, and KB-R7943, a blocker of reversed NCX, inhibit the hyperpolarizing responses to Ca2+-re-addition following Ca2+stores depletion. These finding indicate that LPC and LPI inhibit endothelial hyperpolarization to Ach and histamine independently of G-protein coupled receptors and superoxide anions. Reversed NCX is critical for ER Ca2+refilling in EC. The inhibition of NCX by LPI and LPC underlies diminished endothelium-dependent responses and endothelial dysfunction accompanied by increased levels of these lipids in the blood.
authors.affiliation: Circulatory Physiology Department, Bogomoletz Institute of Physiology NAS of Ukraine, Bogomoletz Str.4, 01024 Kiev, Ukraine; Medical University of Graz, Institute of Molecular Biology and Biochemistry, Graz 8010, Austria. Electronic address: abond01@biph.kiev.ua.
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Bondarenko
authors.affiliation: First Clinic of Internal Medicine, Department of Internal Medicine, University of Genoa, 6 viale Benedetto XV, 16132 Genoa, Italy; IRCCS AOU San Martino - IST Istituto Nazionale per la Ricerca sul Cancro, Largo Benzi 10, 16132 Genoa, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Montecucco
authors.affiliation: Circulatory Physiology Department, Bogomoletz Institute of Physiology NAS of Ukraine, Bogomoletz Str.4, 01024 Kiev, Ukraine.
authors.forename: Olga
authors.initials: O
authors.lastname: Panasiuk
authors.affiliation: Circulatory Physiology Department, Bogomoletz Institute of Physiology NAS of Ukraine, Bogomoletz Str.4, 01024 Kiev, Ukraine.
authors.forename: Vadim
authors.initials: V
authors.lastname: Sagach
authors.affiliation: Department of Physiology of Human and Animals, Melitopol State Pedagogical University, Ukraine.
authors.forename: Nataliya
authors.initials: N
authors.lastname: Sidoryak
authors.affiliation: Division of Cardiology, Foundation for Medical Researches, Department of Internal Medicine, University of Geneva, Av. de la Roseraie 64, CH-1211 Geneva 4, Switzerland.
authors.forename: Karim J
authors.initials: KJ
authors.lastname: Brandt
authors.affiliation: Division of Cardiology, Foundation for Medical Researches, Department of Internal Medicine, University of Geneva, Av. de la Roseraie 64, CH-1211 Geneva 4, Switzerland.
authors.forename: François
authors.initials: F
authors.lastname: Mach
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / Q000819:agonists / Q000378:metabolism; D008244:Lysophosphatidylcholines / Q000494:pharmacology*; D008246:Lysophospholipids / Q000494:pharmacology*; D008297:Male; D008564:Membrane Potentials; D008810:Mice, Inbred C57BL; D043882:Receptors, Cannabinoid / Q000187:drug effects* / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: C530995:BKCa protein, mouse; C526692:GPR55 protein, mouse; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D008244:Lysophosphatidylcholines; D008246:Lysophospholipids; D043882:Receptors, Cannabinoid; D019831:Sodium-Calcium Exchanger; D014665:Vasodilator Agents; C025449:lysophosphatidylinositol; D006632:Histamine; D000109:Acetylcholine
keywords: Endothelial cells; Hyperpolarization; Lysophosphatidylcholine; Lysophosphatidylinositol; Na(+)-Ca(2+) exchanger