Endothelial coordination of cerebral vasomotion via myoendothelial gap junctions containing connexins 37 and 40
Date
2006
Authors
Haddock, Rebecca
Grayson, Thomas
Brackenbury, Therese
Meaney, Kate
Neylon, Craig B
Sandow, Shaun, L
Hill, Caryl
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American Physiological Society
Abstract
Control of cerebral vasculature differs from that of systemic vessels outside the blood-brain barrier. The hypothesis that the endothelium modulates vasomotion via direct myoendothelial coupling was investigated in a small vessel of the cerebral circulation. In the primary branch of the rat basilar artery, membrane potential, diameter, and calcium dynamics associated with vasomotion were examined using selective inhibitors of endothelial function in intact and endothelium-denuded arteries. Vessel anatomy, protein, and mRNA expression were studied using conventional electron microscopy high-resolution ultrastructural and confocal immunohistochemistry and quantitative PCR. Membrane potential oscillations were present in both endothelial cells and smooth muscle cells (SMCs), and these preceded rhythmical contractions during which adjacent SMC intracellular calcium concentration ([Ca2+]i) waves were synchronized. Endothelium removal abolished vasomotion and desynchronized adjacent smooth muscle cell [Ca2+]i waves. N G-nitro-L-arginine methyl ester (10 μM) did not mimic this effect, and dibutyryl cGMP (300 μM) failed to resynchronize [Ca2+] i waves in endothelium-denuded arteries. Combined charybdotoxin and apamin abolished vasomotion and depolarized and constricted vessels, even in absence of endothelium. Separately, 37,43Gap27 and 40Gap27 abolished vasomotion. Extensive myoendothelial gap junctions (3 per endothelial cell) composed of connexins 37 and 40 connected the endothelial cell and SMC layers. Synchronized vasomotion in rat basilar artery is endothelium dependent, with [Ca2+]i waves generated within SMCs being coordinated by electrical coupling via myoendothelial gap junctions.
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Keywords
Keywords: connexin 37; connexin 40; gap junction protein; potassium channel; animal experiment; artery blood flow; article; brain blood flow; brain blood vessel; cell damage; cell function; controlled study; electron microscope; endothelium; male; membrane potentia Connexin; Electron microscopy; Endothelial function; Membrane potential; Potassium channel
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American Journal of Physiology: Heart and Circulatory Physiology
Type
Journal article
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2037-12-31
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