Cholesterol depletion disrupts caveolae and differentially impairs agonist-induced arterial contraction.

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title = "Cholesterol depletion disrupts caveolae and differentially impairs agonist-induced arterial contraction.",
abstract = "OBJECTIVE: This study assessed the role of cholesterol-rich membrane regions, including caveolae, in the regulation of arterial contractility. Methods and Results- Rat tail artery devoid of endothelium was treated with the cholesterol acceptor methyl-beta-cyclodextrin, and the effects on force and Ca2+ handling were evaluated. In cholesterol-depleted preparations, the force responses to alpha1-adrenergic receptors, membrane depolarization, inhibition of myosin light chain phosphatase, and activation of G proteins with a mixture of 20 mmol/L NaF and 60 micro mol/L AlCl3 were unaffected. In contrast, responses to 5-hydroxytryptamine (5-HT), vasopressin, and endothelin were reduced by >50{\%}. The rise in global intracellular free Ca2+ concentration in response to 5-HT was attenuated, as was the generation of Ca2+ waves at the cellular level. By electron microscopy, cholesterol depletion was found to disrupt caveolae. The 5-HT response could be restored by exogenous cholesterol, which also restored caveolae. Western blots showed that the levels of 5-HT2A receptor and of caveolin-1 were unaffected by cholesterol extraction. Sucrose gradient centrifugation showed enrichment of 5-HT2A receptors, but not alpha1-adrenergic receptors, in the caveolin-1-containing fractions, suggesting localization of the former to caveolae. CONCLUSIONS: These results show that a subset of signaling pathways that regulate smooth muscle contraction depends specifically on cholesterol. Furthermore, the cholesterol-dependent step in serotonergic signaling occurs early in the pathway and depends on the integrity of caveolae.",
keywords = "5-hydroxytryptamine, intracellular calcium, endothelin, smooth muscle, caveolae",
author = "Karl Dreja and Marianne Voldstedlund and J{\o}rgen Vinten and J{\o}rgen Tranum-Jensen and Per Hellstrand and Karl Sw{\"a}rd",
note = "The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Department of Experimental Medical Science (013210000), Unit on Vascular Diabetic Complications (013241510), Vascular Physiology (013212034)",
year = "2002",
doi = "10.1161/01.ATV.0000023438.32585.A1",
language = "English",
volume = "22",
pages = "1267--1272",
journal = "Arteriosclerosis, Thrombosis and Vascular Biology",
issn = "1524-4636",
publisher = "Lippincott Williams Wilkins Hagerstown, MD",
number = "8",