Background: We hypothesised that the potential protective effects of endothelial ETB are important in limiting pulmonary vascular muscularisation, vasoconstriction and the development of pulmonary arterial hypertension in response to hypoxia. Methods: EC-specific ETB knockout mice (EC ETB–/–) and control mice (ETBf/f) were subjected to hypobaric hypoxic (10% FiO2) or normoxic conditions for 14 days before assessment of right ventricular pressure and pulmonary vascular morphology and function. Results: During normoxia, no difference in right ventricular pressure was detected between EC ETB–/– (23.7 ± 1.7 mm Hg) and ETBf/f mice (20.2 ± 1.5 mm Hg). Hypoxia induced an exaggerated increase in right ventricular pressure in EC ETB–/– mice (34.4 ± 1.2 mm Hg vs. 24.6 ± 1.4 mm Hg), accompanied by an increase in right ventricular mass. No effect was observed in ETBf/f mice. Endothelin-1 constricted pulmonary arteries from both groups, although maximum response was similar irrespective of inspired oxygen or genotype. Hypoxia increased the percentage of muscularised vessels in both groups of mice, but the percentage increase was significantly greater in EC ETB–/– mice. Conclusions: The potential protective effects of endothelial ETB are important in limiting pulmonary vascular muscularisation and the development of pulmonary arterial hypertension in response to hypoxia.

Keywords:
ETB receptor, Knockout, Endothelin, Pulmonary hypertension
1.
Humbert M, Barst RJ, Robbins IM, Channick RN, Galie N, Boonstra A, Rubin LJ, Horn EM, Manes A, Simonneau G: Combination of bosentan with epoprostenol in pulmonary arterial hypertension: BREATHE-2. Eur Respir J 2004;24:353–359.
2.
Yanagisawa M, Kurihara H, Kimura S, Tomobe Y, Kobayashi M, Mitsui Y, Yazaki Y, Goto K, Masaki T: A novel potent vasoconstrictor peptide produced by vascular endothelial cells. Nature 1988;332:411–415.
3.
Stelzner TJ, O’Brien RF, Yanagisawa M, Sakurai T, Sato K, Webb S, Zamora M, McMurtry IF, Fisher JH: Increased lung endothelin-1 production in rats with idiopathic pulmonary hypertension. Am J Physiol 1992;262:L614–L620.
4.
Frasch HF, Marshall C, Marshall BE: Endothelin-1 is elevated in monocrotaline pulmonary hypertension. Am J Physiol 1999;276:L304–L310.
5.
Nakanishi K, Tajima F, Nakata Y, Osada H, Tachibana S, Kawai T, Torikata C, Suga T, Takishima K, Aurues T, Ikeda T: Expression of endothelin-1 in rats developing hypobaric hypoxia-induced pulmonary hypertension. Lab Invest 1999;79:1347–1357.
6.
Cacoub P, Dorent R, Nataf P, Carayon A, Riquet M, Noe E, Piette JC, Godeau P, Gandjbakhch I: Endothelin-1 in the lungs of patients with pulmonary hypertension. Cardiovasc Res 1997;33:196–200.
7.
Rubin LJ, Badesch DB, Barst RJ, Galie N, Black CM, Keogh A, Pulido T, Frost A, Roux S, Leconte I, Landzberg M, Simonneau G: Bosentan therapy for pulmonary arterial hypertension. N Engl J Med 2002;346:896–903.
8.
Barst RJ, Langleben D, Badesch D, Frost A, Lawrence EC, Shapiro S, Naeije R, Galie N: Treatment of pulmonary arterial hypertension with the selective endothelin-A receptor antagonist sitaxsentan. J Am Coll Cardiol 2006;47:2049–2056.
9.
Firth JD, Ratcliffe PJ: Organ distribution of the three rat endothelin messenger RNAs and the effects of ischemia on renal gene expression. J Clin Invest 1992;90:1023–1031.
10.
Li H, Chen SJ, Chen YF, Meng QC, Durand J, Oparil S, Elton TS: Enhanced endothelin-1 and endothelin receptor gene expression in chronic hypoxia. J Appl Physiol 1994;77:1451–1459.
11.
Davie N, Haleen SJ, Upton PD, Polak JM, Yacoub MH, Morrell NW, Wharton J: ETA and ETB receptors modulate the proliferation of human pulmonary artery smooth muscle cells. Am J Respir Crit Care Med 2002;165:398–405.
12.
Takahashi H, Soma S, Muramatsu M, Oka M, Fukuchi Y: Upregulation of ET-1 and its receptors and remodeling in small pulmonary veins under hypoxic conditions. Am J Physiol Lung Cell Mol Physiol 2001;280:L1104–L1114.
13.
Soma S, Takahashi H, Muramatsu M, Oka M, Fukuchi Y: Localization and distribution of endothelin receptor subtypes in pulmonary vasculature of normal and hypoxia-exposed rats. Am J Respir Cell Mol Biol 1999;20:620–630.
14.
de Nucci G, Thomas R, D’Orleans-Juste P, Antunes E, Walder C, Warner TD, Vane JR: Pressor effects of circulating endothelin are limited by its removal in the pulmonary circulation and by the release of prostacyclin and endothelium-derived relaxing factor. Proc Natl Acad Sci USA 1988;85:9797–9800.
15.
Takayanagi R, Kitazumi K, Takasaki C, Ohnaka K, Aimoto S, Tasaka K, Ohashi M, Nawata H: Presence of non-selective type of endothelin receptor on vascular endothelium and its linkage to vasodilation. FEBS Lett 1991;282:103–106.
16.
Nishida M, Okada Y, Akiyoshi K, Eshiro K, Takoaka M, Gariepy CE, Yanagisawa M, Matsumura Y: Role of endothelin ETB receptor in the pathogenesis of monocrotaline-induced pulmonary hypertension in rats. Eur J Pharmacol 2004;496:159–165.
17.
Ivy DD, Yanagisawa M, Gariepy CE, Gebb SA, Colvin KL, McMurtry IF: Exaggerated hypoxic pulmonary hypertension in endothelin B receptor-deficient rats. Am J Physiol Lung Cell Mol Physiol 2002;282:L703–L712.
18.
Dupuis J, Goresky CA, Fournier A: Pulmonary clearance of circulating endothelin-1 in dogs in vivo: exclusive role of ETB receptors. J Appl Physiol 1996;81:1510–1515.
19.
McCulloch KM, Docherty CC, Morecroft I, MacLean MR: Endothelin B receptor-mediated contraction in human pulmonary resistance arteries. Br J Pharmacol 1996;119:1125–1130.
20.
McCulloch KM, Docherty C, MacLean MR: Endothelin receptors mediating contraction of rat and human pulmonary resistance arteries: effect of chronic hypoxia in the rat. Br J Pharmacol 1998;123:1621–1630.
21.
Balyakina EV, Chen D, Lawrence ML, Manning S, Parker RE, Shappell SB, Meyrick B: ET-1 receptor gene expression and distribution in L1 and L2 cells from hypertensive sheep pulmonary artery. Am J Physiol Lung Cell Mol Physiol 2002;283:L42–L51.
22.
Black SM, Mata-Greenwood E, Dettman RW, Ovadia B, Fitzgerald RK, Reinhartz O, Thelitz S, Steinhorn RH, Gerrets R, Hendricks-Munoz K, Ross GA, Bekker JM, Johengen MJ, Fineman JR: Emergence of smooth muscle cell endothelin B-mediated vasoconstriction in lambs with experimental congenital heart disease and increased pulmonary blood flow. Circulation 2003;108:1646–1654.
23.
Bagnall AJ, Kelland NF, Gulliver-Sloan F, Davenport AP, Gray GA, Yanagisawa M, Webb DJ, Kotelevtsev YV: Deletion of endothelial cell endothelin B receptors does not affect blood pressure or sensitivity to salt. Hypertension 2006;48:286–293.
24.
Kisanuki YY, Hammer RE, Miyazaki J, Williams SC, Richardson JA, Yanagisawa M: Tie2-Cre transgenic mice: a new model for endothelial cell-lineage analysis in vivo. Dev Biol 2001;230:230–242.
25.
Keegan A, Morecroft I, Smillie D, Hicks MN, MacLean MR: Contribution of the 5-HT1B receptor to hypoxia-induced pulmonary hypertension: converging evidence using 5-HT1B-receptor knockout mice and the 5-HT1B/1D-receptor antagonist GR127935. Circ Res 2001;89:1231–1239.
26.
Miller PJ: An elastin stain. Med Lab Technol 1971;28:148–149.
27.
Junqueira LC, Montes GS, Krisztan RM: The collagen of the vertebrate peripheral nervous system. Cell Tissue Res 1979;202:453–460.
28.
Herget J, Palecek F: Experimental chronic pulmonary hypertension. Int Rev Exp Pathol 1978;18:347–406.
29.
MacLean MR, Deuchar GA, Hicks MN, Morecroft I, Shen S, Sheward J, Colston J, Loughlin L, Nilsen M, Dempsie Y, Harmar A: Overexpression of the 5-hydroxytryptamine transporter gene: effect on pulmonary hemodynamics and hypoxia-induced pulmonary hypertension. Circulation 2004;109:2150–2155.
30.
Tada Y, Laudi S, Harral J, Carr M, Ivester C, Tanabe N, Takiguchi Y, Tatsumi K, Kuriyama T, Nichols WC, West J: Murine pulmonary response to chronic hypoxia is strain specific. Exp Lung Res 2008;34:313–323.
31.
Tang L, Luo B, Patel RP, Ling Y, Zhang J, Fallon MB: Modulation of pulmonary endothelial endothelin B receptor expression and signaling: implications for experimental hepatopulmonary syndrome. Am J Physiol Lung Cell Mol Physiol 2007;292:L1467–L1472.
32.
Ivy D, McMurtry IF, Yanagisawa M, Gariepy CE, Le Cras TD, Gebb SA, Morris KG, Wiseman RC, Abman SH: Endothelin B receptor deficiency potentiates ET-1 and hypoxic pulmonary vasoconstriction. Am J Physiol Lung Cell Mol Physiol 2001;280:L1040–L1048.
33.
Ozaki M, Kawashima S, Yamashita T, Ohashi Y, Rikitake Y, Inoue N, Hirata KI, Hayashi Y, Itoh H, Yokoyama M: Reduced hypoxic pulmonary vascular remodeling by nitric oxide from the endothelium. Hypertension 2001;37:322–327.
34.
Steudel W, Scherrer-Crosbie M, Bloch KD, Weimann J, Huang PL, Jones RC, Picard MH, Zapol WM: Sustained pulmonary hypertension and right ventricular hypertrophy after chronic hypoxia in mice with congenital deficiency of nitric oxide synthase 3. J Clin Invest 1998;101:2468–2477.
35.
Fagan KA, Fouty BW, Tyler RC, Morris KG Jr, Hepler LK, Sato K, LeCras TD, Abman SH, Weinberger HD, Huang PL, McMurtry IF, Rodman DM: The pulmonary circulation of homozygous or heterozygous eNOS-null mice is hyperresponsive to mild hypoxia. J Clin Invest 1999;103:291–299.
36.
Giaid A, Yanagisawa M, Langleben D, Michel RP, Levy R, Shennib H, Kimura S, Masaki T, Duguid WP, Stewart DJ: Expression of endothelin-1 in the lungs of patients with pulmonary hypertension. N Engl J Med 1993;328:1732–1739.
37.
Stewart DJ, Levy RD, Cernacek P, Langleben D: Increased plasma endothelin-1 in pulmonary hypertension: marker or mediator of disease? Ann Intern Med 1991;114:464–469.
38.
Langleben D, Dupuis J, Langleben I, Hirsch AM, Baron M, Senecal JL, Giovinazzo M: Etiology-specific endothelin-1 clearance in human precapillary pulmonary hypertension. Chest 2006;129:689–695.
39.
Naomi S, Iwaoka T, Disashi T, Inoue J, Kanesaka Y, Tokunaga H, Tomita K: Endothelin-1 inhibits endothelin-converting enzyme-1 expression in cultured rat pulmonary endothelial cells. Circulation 1998;97:234–236.
40.
Migneault A, Sauvageau S, Villeneuve L, Thorin E, Fournier A, Leblanc N, Dupuis J: Chronically elevated endothelin levels reduce pulmonary vascular reactivity to nitric oxide. Am J Respir Crit Care Med 2005;171:506–513.
41.
Hocher B, Schwarz A, Fagan KA, Thone-Reineke C, El-Hag K, Kusserow H, Elitok S, Bauer C, Neumayer HH, Rodman DM, Theuring F: Pulmonary fibrosis and chronic lung inflammation in ET-1 transgenic mice. Am J Respir Cell Mol Biol 2000;23:19–26.
42.
De Palma M, Venneri MA, Roca C, Naldini L: Targeting exogenous genes to tumor angiogenesis by transplantation of genetically modified hematopoietic stem cells. Nat Med 2003;9:789–795.
43.
De Palma M, Venneri MA, Galli R, Sergi Sergi L, Politi LS, Sampaolesi M, Naldini L: Tie2 identifies a hematopoietic lineage of proangiogenic monocytes required for tumor vessel formation and a mesenchymal population of pericyte progenitors. Cancer Cell 2005;8:211–226.
44.
Wang X, Tong M, Chinta S, Raj JU, Gao Y: Hypoxia-induced reactive oxygen species downregulate ETB receptor-mediated contraction of rat pulmonary arteries. Am J Physiol Lung Cell Mol Physiol 2006;290:L570–L578.
45.
Schwenke DO, Pearson JT, Mori H, Shirai M: Long-term monitoring of pulmonary arterial pressure in conscious, unrestrained mice. J Pharmacol Toxicol Methods 2006; 53:277–283.
46.
Yu AY, Shimoda LA, Iyer NV, Huso DL, Sun X, McWilliams R, Beaty T, Sham JS, Wiener CM, Sylvester JT, Semenza GL: Impaired physiological responses to chronic hypoxia in mice partially deficient for hypoxia-inducible factor 1α. J Clin Invest 1999;103:691–696.
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