Connexin channels provide a target to manipulate brain endothelial calcium dynamics and blood-brain barrier permeability
De Bock, Marijke Culot, Maxime Wang, Nan Bol, Mélissa Decrock, Elke De Vuyst, Elke da Costa, Anaelle Dauwe, Ine Vinken, Mathieu Simon, Alexander M Rogiers, Vera De Ley, Gaspard Evans, William Howard Bultynck, Geert Dupont, Geneviève Cecchelli, Romeo Leybaert, Luc # ×
Lippincott Williams & Wilkins
Journal of Cerebral Blood Flow and Metabolism vol:31 issue:9 pages:1942-1957
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.Journal of Cerebral Blood Flow & Metabolism advance online publication, 8 June 2011; doi:10.1038/jcbfm.2011.86.