title: Endothelin B receptor-mediated regulation of endothelin-1 content and release in cultured porcine aorta endothelial cell.
abstract: Several cardiovascular diseases are associated with an increase in circulating levels of endothelin-1 (ET-1). Little is known about the consequences of this increase on endothelial cell responses with respect to ET-1 production and regulation. Confluent, passage 1, cultured porcine aorta endothelial cells were exposed to exogenous ET-1 (0.1 microM) for 24 h. BQ788 (1 microM, ETB receptor antagonist) but not BQ123 (1 microM, ETA receptor antagonist) significantly (p < 0.05) reduced 125I-ET-1 uptake. The effects of BQ788 were mimicked by dansylcadaverine (0.5 mM) but not nystatin (50 microg/ml). Immunoreactive ET-1 endothelial cell content doubled (p < 0.05) after 24 h of exogenous ET-1 treatment. Bosentan (10 microM, dual ETA/B receptor antagonist) reduced (p < 0.05) immunoreactive ET-1 content in control cells. Bosentan prevented exogenous ET-1-induced endothelial cell ET-1 loading, suggesting that exogenous ET-1 is partly recycled. PreproET-1 mRNA levels were reduced (p < 0.05) by exogenous ET-1 after 24 h, an effect blocked by BQ788 and bosentan. When used alone, both receptor antagonists increased mRNA levels. The results of this study suggest that part of ET-1 is recycled through ETB receptors and subsequently released to contribute to constitutive ET-1 overflow. ET-1 exerts a negative feedback on ET-1 gene transcription, which is dependent on ETB receptor activation and internalization of the complex ET-1/ETB receptor. The maintenance of this negative regulatory loop of ET-1 production may be essential for the normal endothelial physiology.
authors.affiliation: Institut de Cardiologie de Montréal, Center de Recherche, Groupe de Recherche sur le Systeme Nerveux Autonome, Université de Montréal, Québec.
authors.forename: Rocio
authors.initials: R
authors.lastname: Sanchez
authors.forename: Andrew
authors.initials: A
authors.lastname: MacKenzie
authors.forename: Nada
authors.initials: N
authors.lastname: Farhat
authors.forename: Thanh-Dung
authors.initials: TD
authors.lastname: Nguyen
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Stewart
authors.forename: Isabelle
authors.initials: I
authors.lastname: Mercier
authors.forename: Angelino
authors.initials: A
authors.lastname: Calderone
authors.forename: Eric
authors.initials: E
authors.lastname: Thorin
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001011:Aorta / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015152:Blotting, Northern; D000077300:Bosentan; D002478:Cells, Cultured; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008024:Ligands; D009842:Oligopeptides / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011498:Protein Precursors / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology; D013552:Swine
chemical_list: D000959:Antihypertensive Agents; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D008024:Ligands; D009842:Oligopeptides; D010880:Piperidines; D011498:Protein Precursors; D012333:RNA, Messenger; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D013449:Sulfonamides; C086539:BQ 788; D000077300:Bosentan