title: Connexin channels provide a target to manipulate brain endothelial calcium dynamics and blood-brain barrier permeability.
abstract: The cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) is an important factor determining the functional state of blood-brain barrier (BBB) endothelial cells but little is known on the effect of dynamic [Ca(2+)](i) changes on BBB function. We applied different agonists that trigger [Ca(2+)](i) oscillations and determined the involvement of connexin channels and subsequent effects on endothelial permeability in immortalized and primary brain endothelial cells. The inflammatory peptide bradykinin (BK) triggered [Ca(2+)](i) oscillations and increased endothelial permeability. The latter was prevented by buffering [Ca(2+)](i) with BAPTA, indicating that [Ca(2+)](i) oscillations are crucial in the permeability changes. Bradykinin-triggered [Ca(2+)](i) oscillations were inhibited by interfering with connexin channels, making use of carbenoxolone, Gap27, a peptide blocker of connexin channels, and Cx37/43 knockdown. Gap27 inhibition of the oscillations was rapid (within minutes) and work with connexin hemichannel-permeable dyes indicated hemichannel opening and purinergic signaling in response to stimulation with BK. Moreover, Gap27 inhibited the BK-triggered endothelial permeability increase in in vitro and in vivo experiments. By contrast, [Ca(2+)](i) oscillations provoked by exposure to adenosine 5' triphosphate (ATP) were not affected by carbenoxolone or Gap27 and ATP did not disturb endothelial permeability. We conclude that interfering with endothelial connexin hemichannels is a novel approach to limiting BBB-permeability alterations.
authors.affiliation: Department of Basic Medical Sciences, Physiology Group, Ghent University, Ghent, Belgium.
authors.forename: Marijke
authors.initials: M
authors.lastname: De Bock
authors.forename: Maxime
authors.initials: M
authors.lastname: Culot
authors.forename: Nan
authors.initials: N
authors.lastname: Wang
authors.forename: Mélissa
authors.initials: M
authors.lastname: Bol
authors.forename: Elke
authors.initials: E
authors.lastname: Decrock
authors.forename: Elke
authors.initials: E
authors.lastname: De Vuyst
authors.forename: Anaelle
authors.initials: A
authors.lastname: da Costa
authors.forename: Ine
authors.initials: I
authors.lastname: Dauwe
authors.forename: Mathieu
authors.initials: M
authors.lastname: Vinken
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Simon
authors.forename: Vera
authors.initials: V
authors.lastname: Rogiers
authors.forename: Gaspard
authors.initials: G
authors.lastname: De Ley
authors.forename: William Howard
authors.initials: WH
authors.lastname: Evans
authors.forename: Geert
authors.initials: G
authors.lastname: Bultynck
authors.forename: Geneviève
authors.initials: G
authors.lastname: Dupont
authors.forename: Romeo
authors.initials: R
authors.lastname: Cecchelli
authors.forename: Luc
authors.initials: L
authors.lastname: Leybaert
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism*; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002229:Carbenoxolone / Q000494:pharmacology; D002417:Cattle; D002460:Cell Line; D002478:Cells, Cultured; D017630:Connexins / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D010539:Permeability / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D017630:Connexins; D003598:Cytoskeletal Proteins; D014665:Vasodilator Agents; D000255:Adenosine Triphosphate; D002229:Carbenoxolone; D001920:Bradykinin; D002118:Calcium