Increased endothelial exocytosis and generation of endothelin-1 contributes to constriction of aged arteries.
Goel-A; Su-B; Flavahan-S; Lowenstein-CJ; Berkowitz-DE; Flavahan-NA
Circ Res 2010 Jul; 107(2):242-251
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
Circulatory-system; Age-factors; Animal-studies; Laboratory-animals; Dose-response; Pharmacology; Enzyme-inhibitors; Metabolism; Peptides; Recombinant-DNA; Cell-biology; Cellular-reactions; Cardiovascular-system; Pathology;
Author Keywords: aorta; mesenteric arteries; Weibel-Palade bodies; thrombin; von Willebrand factor
Nick Flavahan, Department of Anesthesiology, Johns Hopkins University, Ross-R1159, 720 Rutland Ave, Baltimore, MD 21205
Johns Hopkins University