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


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.
Goel
Aditya
A
Department of Anesthesiology, Johns Hopkins University, Baltimore, MD 21205, USA.
Su
Baogen
B
Flavahan
Sheila
S
Lowenstein
Charles J
CJ
Berkowitz
Dan E
DE
Flavahan
Nicholas A
NA
D000367:Age Factors; D000375:Aging; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism*; D016282:Aspartic Acid Endopeptidases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D065130:Endothelin A Receptor Antagonists; D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism*; D000072396:Endothelin-Converting Enzymes; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects; D005455:Fluorescent Antibody Technique; D006020:Glycopeptides / Q000494:pharmacology; D006834:Hydrazines / Q000494:pharmacology; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors / Q000378:metabolism; D052066:N-Ethylmaleimide-Sensitive Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D010456:Peptides, Cyclic / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D044022:Receptor, Endothelin A / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D013453:Sulfonylurea Compounds / Q000494:pharmacology; D013917:Thrombin / Q000378:metabolism; D015854:Up-Regulation; D014661:Vasoconstriction / Q000187:drug effects; D014841:von Willebrand Factor / Q000378:metabolism
D065130:Endothelin A Receptor Antagonists; D019332:Endothelin-1; D004791:Enzyme Inhibitors; D006020:Glycopeptides; D006834:Hydrazines; D020030:Nitric Oxide Donors; D010456:Peptides, Cyclic; D012333:RNA, Messenger; D044022:Receptor, Endothelin A; C419789:SM 19712; D013449:Sulfonamides; D013453:Sulfonylurea Compounds; D014841:von Willebrand Factor; C084012:1,1-diethyl-2-hydroxy-2-nitrosohydrazine; D019001:Nitric Oxide Synthase; D013917:Thrombin; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; C000606923:ECE1 protein, human; D000072396:Endothelin-Converting Enzymes; D052066:N-Ethylmaleimide-Sensitive Proteins; C498737:Nsf protein, rat; C072247:cyclo(Trp-Asp-Pro-Val-Leu); C008890:phosphoramidon; D019331:NG-Nitroarginine Methyl Ester