title: The role of endothelin-1 and the endothelin B receptor in the pathogenesis of hepatopulmonary syndrome in the rat.
abstract: Endothelin-1 (ET-1) stimulation of endothelial nitric oxide synthase (eNOS) via pulmonary endothelial endothelin B (ET(B)) receptors and pulmonary intravascular macrophage accumulation with expression of inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1) are implicated in experimental hepatopulmonary syndrome (HPS) after common bile duct ligation (CBDL). Our aim was to evaluate the role of ET-1 in the development of experimental HPS. The time course of molecular and physiological changes of HPS and the effects of selective endothelin receptor antagonists in vivo were assessed after CBDL. Effects of ET-1 on intralobar pulmonary vascular segment reactivity and on eNOS expression and activity in rat pulmonary microvascular endothelial cells (RPMVECs) were also evaluated. Hepatic and plasma ET-1 levels increased 1 week after CBDL in association with a subsequent increase in pulmonary microvascular eNOS and ET(B) receptor levels and the onset of HPS. Selective ET(B) receptor inhibition in vivo significantly decreased pulmonary eNOS and ET(B) receptor levels and ameliorated HPS. CBDL pulmonary artery segments had markedly increased ET(B) receptor mediated, nitric oxide dependent vasodilatory responses to ET-1 compared with controls and ET-1 triggered an ET(B) receptor dependent stimulation of eNOS in RPMVECs. Pulmonary intravascular macrophages also accumulated after CBDL and expressed HO-1 and iNOS at 3 weeks. Selective ET(B) receptor blockade also decreased macrophage accumulation and iNOS production. In conclusion, ET-1 plays a central role in modulating pulmonary micovascular tone in experimental HPS.
authors.affiliation: Department of Internal Medicine, Liver Center, University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: Yiqun
authors.initials: Y
authors.lastname: Ling
authors.forename: Junlan
authors.initials: J
authors.lastname: Zhang
authors.forename: Bao
authors.initials: B
authors.lastname: Luo
authors.forename: Daisheng
authors.initials: D
authors.lastname: Song
authors.forename: Lichuan
authors.initials: L
authors.lastname: Liu
authors.forename: Liping
authors.initials: L
authors.lastname: Tang
authors.forename: Cecil R
authors.initials: CR
authors.lastname: Stockard
authors.forename: William E
authors.initials: WE
authors.lastname: Grizzle
authors.forename: David D
authors.initials: DD
authors.lastname: Ku
authors.forename: Michael B
authors.initials: MB
authors.lastname: Fallon
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D003135:Common Bile Duct; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology; D020065:Hepatopulmonary Syndrome / Q000097:blood / Q000209:etiology*; D008026:Ligation; D008297:Male; D019001:Nitric Oxide Synthase / Q000096:biosynthesis; D052250:Nitric Oxide Synthase Type III; D011651:Pulmonary Artery / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044023:Receptor, Endothelin B / Q000502:physiology*
chemical_list: D015415:Biomarkers; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D044023:Receptor, Endothelin B; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat