Long-Term Administration of Endothelin Receptor Antagonist Improves Coronary Endothelial Function in Patients With Early Atherosclerosis

Division of Cardiovascular Diseases, Mayo Clinic Rochester, 200 First St SW, Rochester, MN 55905, USA.
Circulation (Impact Factor: 14.43). 09/2010; 122(10):958-66. DOI: 10.1161/CIRCULATIONAHA.110.967406
Source: PubMed


Endothelin (ET-1) is one of the most potent vasoconstrictors and plays a seminal role in the pathogenesis of atherosclerosis. The present study was designed to test the hypothesis that long-term treatment with an endothelin-A (ET(A)) receptor antagonist improves coronary endothelial function in patients with early coronary atherosclerosis.
Forty-seven patients with multiple cardiovascular risk factors, nonobstructive coronary artery disease, and coronary endothelial dysfunction were randomized in a double-blind manner to either the ET(A) receptor antagonist atrasentan (10 mg) or placebo for 6 months. Coronary endothelium-dependent vasodilation was examined by infusing acetylcholine (10(-6) to 10(-4) mol/L) in the left anterior descending coronary artery. N(G)-monomethyl-l-arginine was administered to a subgroup of patients. Endothelium-independent coronary flow reserve was examined by use of intracoronary adenosine and nitroglycerin. Baseline characteristics and incidence of adverse effects were similar between the 2 groups. There was a significant improvement in percent change of coronary blood flow in response to acetylcholine at 6 months from baseline in the atrasentan group compared with the placebo group (39.67%, 95% confidence interval 23.23% to 68.21%, versus -2.22%, 95% confidence interval -27.37% to 15.28%; P<0.001). No significant difference in the percent change of coronary artery diameter or change in coronary flow reserve was demonstrated. Coronary blood flow, coronary artery diameter, and the effect of N(G)-monomethyl-l-arginine were similar between the groups at baseline and at 6 months.
This study demonstrates that 6-month treatment with atrasentan improves coronary microvascular endothelial function and supports the role of the endogenous endothelin system in the regulation of endothelial function in early atherosclerosis in humans. Clinical Trial Registration Information- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00271492.

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Available from: Eugenia Raichlin, Jan 31, 2014
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    • "Indeed, both oxidative stress and increased ET-1 bioactivity have been implicated in age-dependent impaired endothelial cell function (Barton, 2010; Seals et al., 2011), which is associated with arterial stiffening and sclerosis (Zieman et al., 2005), and consecutive renal injury (Zhou et al., 2008). Antagonizing ET-1-dependent effects have previously been found to improve endothelial function in individuals with early coronary artery disease (Reriani et al., 2010), and even to reverse renal aging and glomerular vascular injury (Ortmann et al., 2004). Moreover, treatment with an ET A receptor antagonist reduces arterial stiffness in patients with chronic kidney disease (Dhaun et al., 2009). "
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    ABSTRACT: Aims Aging, a physiological process and main risk factor for cardiovascular and renal diseases, is associated with endothelial cell dysfunction partly resulting from NADPH oxidase-dependent oxidative stress. Because increased formation of endothelium-derived endothelin-1 (ET-1) may contribute to vascular aging, we studied the role of NADPH oxidase function in age-dependent contractions to ET-1. Main methods Renal arteries and abdominal aortas from young and old C57BL6 mice (4 and 24 months of age) were prepared for isometric force measurements. Contractions to ET-1 (0.1-100 nmol/L) were determined in the presence and absence of the NADPH oxidase-selective inhibitor gp91ds-tat (3 μmol/L). To exclude age-dependent differential effects of NO bioactivity between vascular beds, all experiments were conducted in the presence of the NO synthase inhibitor L-NAME (300 μmol/L). Key findings In young animals, ET-1-induced contractions were 6-fold stronger in the renal artery than in the aorta (p < 0.001); inhibition of NADPH oxidase by gp91ds-tat reduced responses to ET-1 by 50% and 72% in the renal artery and aorta, respectively (p < 0.05). Aging had no effect on NADPH oxidase-dependent and -independent contractions to ET-1 in the renal artery. In contrast, contractions to ET-1 were markedly reduced in the aged aorta (5-fold, p < 0.01 vs. young) and became insensitive to gp91ds-tat. Significance The results suggest an age-dependent heterogeneity of NADPH oxidase-mediated vascular contractions to ET-1, demonstrating an inherent resistance to functional changes in the renal artery but not in the aorta with aging. Thus, local activity of NADPH oxidase differentially modulates responses to ET-1 with aging in distinct vascular beds.
    Life Sciences 11/2014; 118(2):226-231. DOI:10.1016/j.lfs.2013.12.021 · 2.70 Impact Factor
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    • "Increased ET-1 levels were reported in the ED patients with or without VRFs and in the patients with overt vascular disease.45293031 The blockade of ETa receptors improved the endothelial function in the patients with early atherosclerosis, suggesting a pathogenetic role of increased ET-1 levels in endothelial dysfunction.32 PDE5 inhibition downregulates the ET-1 system,33 which explains the reduced levels of ET-1 in the men with ED and VRFs treated with PDE5i.151734 "
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    ABSTRACT: The number of the circulating angiogenic cells (CACs) and colony forming units (CFUs) derived from cultured circulating mononuclear cells (MNCs) represents a laboratory surrogate for endothelial cell repair ability. The serum of men with erectile dysfunction (ED) and vascular risk factors (VRFs) showed an increased level of endothelial cell damage/dysfunction markers and reduced the numbers of CACs and CFUs derived from the cells of healthy men. We analyzed whether treating men with ED and VRFs with the selective phosphodiesterase type 5 inhibitor tadalafil improved the endothelial cell repair ability and reduced the levels of the serum markers of endothelial cell damage/dysfunction. MNCs from healthy men were cultured with 20% serum from 36 ED patients to obtain CACs and CFUs. The ED patients were evaluated before and after 4 weeks of treatment with tadalafil (20 mg every other day) or with a placebo. The tadalafil treatment improved erectile function (P = 0.0028), but had no effect on the inhibitory effects of serum from ED patients on the CACs and CFUs derived from healthy men. The levels of endothelin-1 (P = 0.011) and tissue type plasminogen activator (P = 0.005) were reduced after treatment compared to baseline and those of the placebo group, whereas no changes were observed in the E-selectin levels. The tadalafil treatment in the ED patients with VRFs resulted in only a modest effect on the laboratory measures of the endothelial cell damage/dysfunction and repair ability. The proposed beneficial effect of phosphodiesterase type 5 inhibition on vascular homeostasis requires further analysis.
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    • "Invasive coronary physiology was assessed at baseline and after 6 months in 47 subjects randomized to daily placebo vs an ET antagonist.16 While baseline flow increased by 15.3 cc/minute in treated subjects compared to 5.6 cc/minute in those taking placebo, this trend did not reach statistical significance (P = .25). "
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    ABSTRACT: Heterogeneity of resting perfusion may be due in part to up-regulation of coronary vasoconstriction via endothelin (ET) type A receptors, as homogeneity increases during subsequent vasodilatory hyperemia. Therefore, we conducted a mechanistic study using an ET receptor antagonist to determine if it could alter the homogeneity of myocardial perfusion. Included subjects demonstrated a low myocardial perfusion homogeneity index (HI) compared to normal volunteers. Four serial cardiac positron emission tomography Rb-82 scans were performed 2 weeks apart. Before the middle two scans, subjects were randomized to receive either darusentan first then placebo or visa versa. Absolute flow and coronary flow reserve were quantified for each study. Rest flow was adjusted for the pressure-rate product (PRP). We screened 37 subjects and randomized 20 who satisfied entry criteria. Rest HI increased significantly while taking darusentan (0.39 ± 0.10 vs 0.33 ± 0.04 on placebo, P = .030, compared to a normal range of 0.52 ± 0.10) without an increase in the PRP (6,859 ± 1,503 vs 6,976 ± 1,092, P = .79), leading to a higher adjusted flow at rest (0.69 ± 0.18 cc/minute/g at 7,000 PRP vs 0.59 ± 0.07 with placebo). Antagonism of the type A ET receptor increases homogeneity of resting myocardial perfusion. The mechanism appears to be increased absolute rest flow without an increase in either the PRP or myocardial perfusion during hyperemia. Our translational results are consistent with one mechanism for the observed heterogeneity of myocardial perfusion in humans.
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