title: Atherosclerosis affects calcium signalling in endothelial cells from apolipoprotein E knockout mice before plaque formation.
abstract: Little is known about how hypercholesterolaemia affects Ca(2+) signalling in the vasculature of ApoE(-/-) mice, a model of atherosclerosis. Our objectives were therefore to determine (i) if hypercholesterolaemia alters Ca(2+) signalling in aortic endothelial cells before overt atherosclerotic lesions occur, (ii) how Ca(2+) signals are affected in older plaque-containing mice, and (iii) whether Ca(2+) signalling changes were translated into contractility differences. Using confocal microscopy we found agonist-specific Ca(2+) changes in endothelial cells. ATP responses were unchanged in ApoE(-/-) cells and methyl-β-cyclodextrin, which lowers cholesterol, was without effect. In contrast, Ca(2+) signals to carbachol were significantly increased in ApoE(-/-) cells, an effect methyl-β-cyclodextrin reversed. Ca(2+) signals were more oscillatory and store-operated Ca(2+) entry decreased as mice aged and plaques formed. Despite clearly increased Ca(2+) signals, aortic rings pre-contracted with phenylephrine had impaired relaxation to carbachol. This functional deficit increased with age, was not related to ROS generation, and could be partially rescued by methyl-β-cyclodextrin. In conclusion, carbachol-induced calcium signalling and handling are significantly altered in endothelial cells of ApoE(-/-) mice before plaque development. We speculate that reduction in store-operated Ca(2+) entry may result in less efficient activation of eNOS and thus explain the reduced relaxatory response to CCh, despite the enhanced Ca(2+) response.
authors.affiliation: Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom. Electronic address: cprender@liv.ac.uk.
authors.forename: Clodagh
authors.initials: C
authors.lastname: Prendergast
authors.affiliation: Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Quayle
authors.affiliation: Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom.
authors.forename: Theodor
authors.initials: T
authors.lastname: Burdyga
authors.affiliation: Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom.
authors.forename: Susan
authors.initials: S
authors.lastname: Wray
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology; D001057:Apolipoproteins E / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D019540:Area Under Curve; D050197:Atherosclerosis / Q000378:metabolism / Q000473:pathology; D020013:Calcium Signaling / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology; D002784:Cholesterol / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012372:ROC Curve
chemical_list: D001057:Apolipoproteins E; D002217:Carbachol; D002784:Cholesterol
keywords: Apolipoprotein-E knockout mice; Calcium signalling; Endothelium; Hypercholesterolaemia