Decreased number of caveolae in endothelial cells impairs the relaxation induced by acetylcholine in hypertensive rat aortas

• Published in: European journal of pharmacology 2010-02, Vol.627 (1), p.251-257
• Main Authors: Rodrigues, Gerson J., Restini, Carolina B.A., Lunardi, Claure N., Neto, Mário dos Anjos, Moreira, Jorge E., Bendhack, Lusiane M.
• Format: Article
• Language: English
• Subjects: Acetylcholine; Acetylcholine - pharmacology; Animals; Aorta - drug effects; Aorta - metabolism; Aorta - pathology; Aorta - physiopathology; Arterial hypertension. Arterial hypotension; Biological and medical sciences; Blood and lymphatic vessels; Calcium - metabolism; Cardiology. Vascular system; Caveola; Caveolae - drug effects; Caveolae - metabolism; Cytosolic calcium; Endothelial cell; Endothelial Cells - drug effects; Endothelial Cells - metabolism; Endothelial Cells - pathology; Endothelial Cells - ultrastructure; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Flow Cytometry; Hypertension - metabolism; Hypertension - pathology; Hypertension - physiopathology; In Vitro Techniques; Medical sciences; Microscopy, Confocal; Microscopy, Electron; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; Muscle, Smooth, Vascular - pathology; Nitric oxide; Nitric Oxide - biosynthesis; Pharmacology. Drug treatments; Rats; Renal hypertension; Vasodilation - drug effects
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/j.ejphar.2009.11.010

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-β-ciclodextrin. The potency (pD 2) and the maximum relaxant effect to acetylcholine were greater in 2K than in 2K-1C aortas. Methyl-β-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-β-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-β-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-β-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-β-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.