title: Decreased number of caveolae in endothelial cells impairs the relaxation induced by acetylcholine in hypertensive rat aortas.
abstract: The present study was designed to investigate the contribution of endothelial cell caveolae to vascular relaxation in aortas from a normotensive (2K) and renal hypertensive (2K-1C) rat. For that purpose, concentration-effect curves to acetylcholine were constructed in 2K and 2K-1C intact endothelium aortic rings, in the absence or in the presence of the caveolae disassembler methyl-beta-ciclodextrin. The potency (pD(2)) and the maximum relaxant effect to acetylcholine were greater in 2K than in 2K-1C aortas. Methyl-beta-ciclodextrin reduced the pD(2) in 2K and the maximum relaxant effect in both 2K and 2K-1C. The quantification of the caveolae number by electronic microscopy has shown a larger number of caveolae in 2K than in 2K-1C endothelial cells, which was reduced by methyl-beta-ciclodextrin in both 2K and 2K-1C. The production of NO stimulated with acetylcholine was greater in 2K than in 2K-1C endothelial cells, and this effect was impaired by methyl-beta-ciclodextrin in both 2K and 2K-1C. The cytosolic Ca(2+) concentration ([Ca(2+)]c) was simultaneously measured in endothelial and smooth muscle cells stimulated with acetylcholine by confocal image of aortic slices. Acetylcholine produced a greater [Ca(2+)]c increase in 2K than in 2K-1C endothelial cells, which response was inhibited by methyl-beta-ciclodextrin only in 2K cells. In smooth muscle cells the reduction of [Ca(2+)]c was higher in 2K than in 2K-1C. This effect was inhibited by methyl-beta-ciclodextrin only in 2K cells. Taken together, our results suggest that the decreased number of caveolae in the endothelial cells from 2K-1C rat aortas is involved in the impaired effect of acetylcholine on [Ca(2+)]c and NO.
authors.affiliation: Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP-Brazil. gerson@usp.br
authors.forename: Gerson J
authors.initials: GJ
authors.lastname: Rodrigues
authors.forename: Carolina B A
authors.initials: CB
authors.lastname: Restini
authors.forename: Claure N
authors.initials: CN
authors.lastname: Lunardi
authors.forename: Mário Dos Anjos
authors.initials: Mdos A
authors.lastname: Neto
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Moreira
authors.forename: Lusiane M
authors.initials: LM
authors.lastname: Bendhack
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D002118:Calcium / Q000378:metabolism; D021941:Caveolae / Q000187:drug effects / Q000378:metabolism*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D006973:Hypertension / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology*; D066298:In Vitro Techniques; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009569:Nitric Oxide / Q000096:biosynthesis; D051381:Rats; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D009569:Nitric Oxide; D000109:Acetylcholine; D002118:Calcium