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Circ Res. 2010 Jul 23;107(2):242-51. doi: 10.1161/CIRCRESAHA.109.210229. Epub 2010 Jun 3.

Increased endothelial exocytosis and generation of endothelin-1 contributes to constriction of aged arteries.

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  • 1Department of Anesthesiology, Johns Hopkins University, Baltimore, MD 21205, USA.

Abstract

RATIONALE:

Circulating levels of endothelin (ET)-1 and endogenous ET(A)-mediated constriction are increased in human aging. The mechanisms responsible are not known.

OBJECTIVE:

Investigate the storage, release, and activity of ET-1 system in arteries from young and aged Fischer-344 rats.

METHODS AND RESULTS:

After NO synthase inhibition (L-NAME), thrombin contracted aged arteries, which was inhibited by endothelial denudation, ET(A) receptor antagonism (BQ123), and ECE inhibition (phosphoramidon, SM19712) or by inhibiting exocytosis (TAT-NSF, N-ethylmaleimide-sensitive factor inhibitor). Thrombin did not cause endothelium-dependent contraction of young arteries. In aged but not young arteries, thrombin rapidly increased ET-1 release, which was abolished by endothelium denudation or TAT-NSF. L-NAME did not affect ET-1 release. ET-1 immunofluorescent staining was punctate and distinct from von Willebrand factor (VWF). VWF and ET-1 immunofluorescent intensity was similar in young and aged quiescent arteries. Thrombin rapidly increased ET-1 staining and decreased VWF staining in aged but had no effect in young aortas. After L-NAME, thrombin decreased VWF staining in young aortas. NO donor DEA-NONOate (1 to 100 nmol/L) reversed thrombin-induced exocytosis in young (VWF) but not aged L-NAME-treated aortas (VWF, ET-1). Expression of preproET-1 mRNA and ECE-1 mRNA were increased in aged compared to young endothelium. BigET-1 levels and contraction to exogenous BigET-1 (but not ET-1) were also increased in aged compared to young arteries.

CONCLUSIONS:

The stimulated exocytotic release of ET-1 is dramatically increased in aged endothelium. This reflects increased reactivity of exocytosis, increased expression and storage of ET-1 precursor peptides, and increased expression of ECE-1. Altered endothelial exocytosis of ET-1 and other mediators may contribute to cardiovascular pathology in aging.

PMID:
20522806
[PubMed - indexed for MEDLINE]
PMCID:
PMC2909353
Free PMC Article

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