Big Endothelin-1 Concentrations Research Articles

Transmyocardial extraction of endothelin-1 correlates with increased microvascular resistance following percutaneous coronary intervention

Abstract Introduction Coronary microvascular dysfunction (CMD) can persist following successful percutaneous coronary intervention (PCI). Endothelin-1 (ET-1) is a potent vasoconstrictor and may be an important mediator of CMD. We sought to assess the trans-myocardial gradient (TMG – coronary sinus minus coronary root levels) of ET-1 and its precursor - Big ET-1 and assess the correlation with pressure-wire indices of CMD: coronary flow reserve (CFR) and index of microvascular resistance (IMR). Methods Paired blood samples from the aortic root and coronary sinus were collected before and after pressure wire guided PCI from patients with stable angina. Plasma was then analysed using specific enzyme linked immunosorbent assay (ELISA) for quantification of ET-1 and Big ET-1 and correlated with pressure-wire data. Results Samples were analysed from 66 patients. Both mean ET-1 and Big ET-1 concentrations increased post-PCI in both the aorta (ET-1: 1.0±0.4 pg/ml to 1.4±0.4 pg/ml, p<0.0001 and Big ET-1: 2.8±1.3 pg/ml to 3.4±1.6 pg/ml, p<0.0001) and coronary sinus (ET-1: 1.0±0.3 pg/ml to 1.2±0.3 pg/ml, p=0.03 and Big ET-1: 3.2±1.7 pg/ml to 3.8±1.5 pg/ml, p=0.01). TMG extraction of ET-1 increased following PCI: 0.05±0.25 pg/ml vs.-0.20±0.41 pg/ml, p=0.01. In contrast, there was TMG release of Big ET-1 before and after PCI: 0.46±1.26 pg/ml vs. 0.38±1.03 pg/ml, p=0.52. ET-1 extraction correlated with IMR post-PCI (Pearson's r=0.293, p=0.02). Patients with CFR<2 post-PCI demonstrated a numerical trend towards higher mean ET-1 extraction than those with preserved CFR post-PCI (0.30±0.51 pg/ml vs. 0.16±0.42 pg/ml, p=0.31) as did those with criteria for Type 4a Myocardial Infarction compared with those without (0.39±0.57 vs. 0.15±0.41, p=0.11). Conclusions ET-1 and Big ET-1 significantly increase post-PCI. Trans-myocardial extraction of ET-1 increases post-PCI and correlates with post-PCI CMD. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Jon Moulton Charity Trust.NIHR Cambridge Biomedical Research Centre Biomedical Resources Grant. TMG of ET-1 and Big ET-1ET-1 extraction and post-PCI IMR

Combined baseline and one-month changes in big endothelin-1 and brain natriuretic peptide plasma concentrations predict clinical outcomes in patients with left ventricular dysfunction after acute myocardial infarction: Insights from the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS) study

ObjectiveIncreased levels of neuro-hormonal biomarkers predict poor prognosis in patients with acute myocardial infarction (AMI) complicated by left ventricular systolic dysfunction (LVSD). The predictive value of repeated (one-month interval) brain natriuretic peptides (BNP) and big-endothelin 1 (BigET-1) measurements were investigated in patients with LVSD after AMI. MethodsIn a sub-study of the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS trial), BNP and BigET-1 were measured at baseline and at 1month in 476 patients. ResultsWhen included in the same Cox regression model, baseline BNP (p=0.0003) and BigET-1 (p=0.026) as well as the relative changes (after 1month) from baseline in BNP (p=0.049) and BigET-1 (p=0.045) were predictive of the composite of cardiovascular death or hospitalization for worsening heart failure. Adding baseline and changes in BigET-1 to baseline and changes in BNP led to a significant increase in prognostic reclassification as assessed by integrated discrimination improvement index (5.0%, p=0.01 for the primary endpoint). ConclusionsBoth increased baseline and changes after one month in BigET-1 concentrations were shown to be associated with adverse clinical outcomes, independently from BNP baseline levels and one month changes, in patients after recent AMI complicated with LVSD. This novel result may be of clinical interest since such combined biomarker assessment could improve risk stratification and open new avenues for biomarker-guided targeted therapies. Key messagesIn the present study, we report for the first time in a population of patients with reduced LVEF after AMI and signs or symptoms of congestive HF, that increased baseline values of BNP and BigET-1 as well as a further rise of these markers over the first month after AMI, were independently predictive of future cardiovascular events. This approach may therefore be of clinical interest with the potential of improving risk stratification after AMI with reduced LVEF while further opening new avenues for biomarker-guided targeted therapies.

Serum big endothelin-1 as a biomarker in oral squamous cell carcinoma patients: an analytical study.

Detection of abnormally elevated levels of molecules in patients with oral cancer may be useful in early diagnosis. These markers can be included in current Histopathology grading and in TNM staging systems of Oral Squamous Cell Carcinoma (OSCC) to make it more efficient. Several pro-angiogenic molecules have been assessed for the same reason. Endothelin-1 (ET-1) is a vasoactive peptide associated with the development and spread of many solid tumors, including Squamous Cell Carcinoma (SCC), but its utility in OSCC has not been confirmed. Objective This study aims to evaluate the role of the serum big ET-1 as a biomarker of OSCC, by correlating it with the clinical staging and the histopathological grading.Material and Methods Serum levels of big ET-1 measured by the sandwich Enzyme-Linked Immunosorbent Assay (ELISA) in 40 OSCC cases were compared with the levels from the control group using independent t-test. Clinical stages and histopathological grades of OSCC cases were compared in relation to their mean levels of serum big ET-1, one using the Analysis of Variance (ANOVA) test and the other the independent t-test, respectively. The significance of the mean difference between the groups was evaluated by Tukey’s multiple comparison test. All statistical analyses were performed on GraphPad statistical software version 5.0.Results By comparing the mean of the big ET-1 concentrations of cases and controls, the independent t-test revealed significant higher big ET-1 concentration of OSCC cases when compared to controls (p<0.0001). Tukey’s multiple comparison test also revealed statistically significant difference among all OSCC stages in relation to the mean levels of serum big ET-1. However, the mean of the big ET-1 concentrations of cases of grade I and of grade II did not differ statistically (p=0.729).Conclusion Serum big ET-1 levels may be useful as a diagnostic tool in OSCC and as an adjunct to OSCC staging. However, its use as a prognostic marker warrants larger prospective studies.

Endothelin 1 in healthy foals and in foals affected by neonatal diseases

In newborn babies, endothelin 1 (ET-1), a potent vasoconstrictor, increases during septicemia and severe respiratory syndromes. Because equine neonatal sepsis (ENS) and perinatal asphyxia syndrome (PAS) are major causes of morbidity and mortality in newborn foals and because no information on the concentration of ET-1 in healthy and sick foals has been reported yet, the aims of this study were (1) to define the serum concentration of Big ET-1 in healthy neonatal foals during the first week of age; (2) to preliminarily explore the diagnostic and prognostic role of Big ET-1 during ENS and PAS. Six healthy and 23 sick foals affected by ENS and/or PAS were enrolled in the study. In healthy foals, Big ET-1 concentration increased in the first hours of life until 24 hours after birth, and it remained constant during the first 3 days, then gradually decreased becoming significantly lower from Day 4 onward (P < 0.05). In sick foals, only 26.1% of animals showed higher values of Big ET-1 than controls at admission, and no difference between surviving and nonsurviving foals was found. Because in nonsurviving foals, Big ET-1 remained over the maximum value recorded in clinically healthy horses or, when normal at admission, increased over time; this study suggested that repeated measurement of Big ET-1 during hospitalization may be helpful in monitoring the course of the disease. In conclusion, possible prognostic information may be obtained by repeated analysis of Big ET-1 during hospitalization, but further studies are needed.

Prognostic value of NT-proBNP and big ET-1 in severe heart failure: significance of NT-proBNP and big ET-1 in cardiovascular diseases combining with severe heart failure

目的 探讨两检测指标血浆N末端B型钠尿肽原(NT-proBNP)和大内皮素-1(big ET-1)之间,两指标与心力衰竭(心衰)伴心房颤动(Af)、心衰伴肺动脉高压(PAH)等心血管病的关系,以及两指标对严重心衰患者半年期预后的预测价值.方法 阜外医院严重心衰患者132人,测定他们入院时的血浆LgNT-proBNP和big ET-1浓度(酶联免疫法)以及纽约心脏病协会心功能分级(NYHA分级)、左室射血分数(LVEF)等指标.随访观察患者出院后半年内心血管事件的再发生.结果 严重心衰患者132人(NYHA Ⅲ-Ⅳ级,年龄24～80岁,男83人,女49人,LVEF 13%～66%),其血浆LgNT-proBNP与big ET-1呈正相关(r=0.414,P=0.000).有、无Af的两组间big ET-1水平比较差异有统计学意义(P=0.022);有、无PAH的两组间LgNT-proBNP和big ET-1浓度差异均有统计学意义(P=0.019,P=0.000).以big ET-1诊断严重心衰患者伴PAH的ROC曲线下面积为0.74(95%CI:0.65～0.83,P=0.000),以4.09 fmol/ml为big ET-1诊断心衰伴PAH的cutoff值时,灵敏度为71.4%,特异度67.8%.经过6个月的随访,132例严重心衰患者中,有20例发生心源性死亡(15.2%),有25例因心脏原因再住院(18.9%).Cox比例风险模型分析显示,包括了年龄、性别、NYHA分级、LVEF、LgNT-proBNP、big ET-1等指标后,只有NT-proBNP是独立的心脏事件再发生的预后因素,RR为5.30(95%CI:2.07～13.55,P=0.001).Logistic回归显示也只有NT-proBNP是独立的心源性死亡发生的危险因素,OR为13.67(95%CI:2.59～72.25,P=0.002).big ET-1、LVEF、NYHA分级等指标对严重心衰患者心血管事件再发生没有预后价值.结论 NT-proBNP与big ET-1间可能存在相互作用;严重心衰伴Af的患者可能有内皮细胞损伤和功能异常;big ET-1可辅助诊断严重心衰患者伴发PAH;NT-proBNP可用于严重心衰患者半年期预后的评估,而big ET-1没有此预测价值。

Endothelin-1 in Humans Is Increased by Oxygen-Derived Radicals Ex Vivo and In Vivo

Endothelin-1, angiotensin II, and oxygen-derived radicals are pivotal factors in the development and progression of atherosclerosis. In vitro studies suggest that generation of oxygen-derived radicals by angiotensin II is an...

Haemodynamic and renal effects of endothelin receptor antagonism in patients with chronic kidney disease

Endothelin-1 (ET-1) has been implicated in the pathophysiology of chronic kidney disease (CKD) and ET receptor blockade has shown renoprotective effects in animals. We examined the haemodynamic and renal effects of an ET receptor antagonist, TAK-044, in patients with CKD. Seven patients with CKD (mean arterial pressure 103 mmHg; mean plasma creatinine 3.5 mg/dl) received three 15 min intravenous infusions, each separated by at least 7 days, of either placebo or TAK-044 (100 or 750 mg) in a randomized, double blind crossover study. Systemic and renal haemodynamics, and plasma immunoreactive ET-1, big ET-1 and C-terminal fragment concentrations, were determined before and after the infusions of placebo and drugs. Compared with placebo, TAK-044 reduced mean arterial pressure (MAP) (100 mg: 7.4 +/- 1.9 mmHg, 750 mg: 8.4 +/- 2.3 mmHg, P < 0.01) and systemic vascular resistance index (100 mg: 650 +/- 140 dyne.s.cm(-5).m(-2), 750 mg: 829 +/- 141 dyne.s.cm(-5).m(-2), P < 0.01) at both doses. TAK-044 increased cardiac index and heart rate to a similar degree at both doses. With regards to renal haemodynamics, TAK-044 had no significant effect on the glomerular filtration rate at either dose but tended to increase renal plasma flow (100 mg: 9.6 +/- 5.0 ml/min, 750 mg: 25.3 +/- 19.5 ml/min) and decreased the effective filtration fraction (100 mg: 3.6 +/- 1.1%, 750 mg: 4.7 +/- 1.7%, P < 0.01), in a dose-dependent manner. TAK-044 had no significant effect on sodium or lithium clearance, or on fractional excretion of sodium and lithium. Plasma ET-1 concentrations rose more than two-fold after 750 mg TAK-044 while big ET-1 and C-terminal fragment concentrations were unchanged. These findings suggest an important role for ET-1 in controlling systemic and renal haemodynamics in patients with CKD. The antihypertensive and potentially renoprotective actions of ET receptor antagonists shown in this study may prove useful in slowing the progression of CKD. Clinical trials are now needed to address these key questions for CKD.

Prognosis of Colorectal Cancer Patients with Elevated Endothelin-1 Concentrations

Prognostic indicators from clinical, laboratory and pathological data of patients with colorectal cancer are essential to identify high-risk groups in whom adjuvant therapy could be beneficial. Endothelin-1 (ET-1), a growth factor, has been associated with the development and spread fo solid tumours. This prospective study was performed to determine whiter preoperative plasma big ET-1 concentrations might be useful as a prognostic indicator in patients with colorectal carcinoma. Overall, 65 consecutive patients with colorectal cancer confirmed by biopsy were include prospectively in this study from 1998 to 2001. Plasma samples from a peripheral vein were obtained prior to surgery. Univariant analysis of survival used age (less than or more than 70 years), gender, Dukes' stage (A/B vs C), tumour size (less than or more than 50 mm), vascular invasion, and plasma big ET-1 concentrations, and significant factors were then analysed using a Cox regression model. Three variables, age, Dukes' tumour stage and plasma big ET-1 concentration, and prognostic significance (p < 0.05). Factors associated with a poorer prognosis were age more than 70 years (p = 0.02), Dukes' C (p = 0.04) and plasma big ET-1 concentration more than 4.2 pg/mL (p = 0.02). The Cox regression model identified the same three variables as having independent prognostic value for overall survival. Preoperative plasma big ET-1 concentration may be useful in predicting overall survival in patients with colorectal cancer. Plasma big ET-1 concentrations may be useful in the selection of high-risk, lymph node-negative patients with colorectal cancer for adjuvant therapy.

Endothelin-1 mRNA and protein in vascular wall cells is increased by reactive oxygen species.

A dysregulated metabolism of oxygen-derived free radicals, nitric oxide and endothelin-1(ET-1) in conditions such as hypercholesterolaemia or hypertension may promote the development of atherosclerosis. We therefore subjected cultured human umbilical vein endothelial cells and coronary artery smooth muscle cells to oxidative stress induced by xanthine oxidase or hydrogen peroxide and observed alterations in ET-1 metabolism. Incubation with oxygen-derived free radicals increased preproET-1 promoter activity, ET-1 mRNA synthesis and big ET-1 concentrations in both cell types. This interaction of oxidative stress and ET-1 expression may be relevant in atherogenic conditions such as hypercholesterolaemia and hypertension since our data indicate that oxidative stress further aggravates the injurious effects attributed to ET-1.

Nitric oxide inhalation modulates endothelin-1 and big endothelin-1 after left ventricular assist device implantation

Purpose: Nitric oxide inhalation therapy is now an established therapy in the treatment of right ventricular dysfunction due to pulmonary hypertension after left ventricular assist device (LVAD) implantation. Inhaled nitric oxide (iNO) decreases right ventricular afterload by its selective vasodilating effect on the pulmonary circulation. It is known that endothelin-1 (ET-1) contributes to pulmonary hypertension. The effects of iNO on circulating ET-1 and big endothelin (big ET-1) in LVAD-patients were investigated in this study. Methods: On weaning from cardiopulmonary bypass (CPB) 15 consecutive patients were treated with iNO because of right ventricular compromise secondary to pulmonary hypertension. Plasma ET-1 and big ET-1 concentrations were measured preoperatively, on CPB prior to iNO, 12, 24, and 48 hrs. postoperatively, as well as 72 hrs after cessation of iNO. Results: Mean initial iNO dose was 33 ppm (20-40 ppm). NO therapy was successfully weaned in all patients without a rebound phenomenon. ET-1 and big ET-1 were increased preoperatively (1.50 1/1.9 and 3.87 1/3.0 fmol/ml, respectively). ET-1 concentrations were highest on cardiopulmonary bypass (2.001/1.56 fmol/ml). ET-1 and big ET-1 decreased significantly during iNO therapy and were lowest 72 hrs after cessation of iNO (Table 1). The iNO dose and plasma ET-1 levels correlated significantly (p,0.001). A significant correlation was also found between ET-1 and PA-pressures, PVR and PVR/SVR ratio, but not with CI and SVR. Conclusion: Since it is known, that ET-1 mediates pulmonary hypertension, we suggest a two-fold effect of iNO therapy: first a selective vasodilation of the pulmonary vasculature and second NO-mediated inhibition of one of the most potent vasoconstrictors of pulmonary vessels: ET-1. Table 1

Plasma endothelin-1 and big endothelin-1 levels in superior and inferior vena cava during protracted antiorthostatic hypokinetic/hypodynamia in rats.

The plasma levels of endothelin-1 and big endothelin-1 were evaluated in blood of rats in the superior and inferior vena cava, in normal posture (synchronous controls), and after 12 days head-down suspension and 1 day recovery in normal posture. In synchronous controls, the mean plasma concentration of endothelin-1 in inferior vena cava or superior vena cava was almost the same (5.89+/-0.63 pmol/l and 5.67+/-0.64 pmol/l, respectively), whereas the mean plasma concentration of big endothelin-1 was higher (p<0.05) in superior vena cava compared to inferior vena cava (5.49+/-0.75 pmol/l and 1.39+/-0.15 pmol/l, respectively). In samples from superior vena cava of head-down suspended rats big endothelin-1 levels were significantly lower (p<0.05) up to day 9 of suspension, compared to non-suspended synchronous controls, whereas endothelin-1 values were higher (p<0.05). Big endothelin-1 concentration was higher (p<0.05) in inferior vena cava compared to non-suspended synchronous controls. The behaviour of endothelin-1 was more complex, endothelin-1 levels were lower (p<0.05) on day 1 of head-down suspension and higher (p<0.05) in samples taken on days 9 and 12. After 1 day recovery endothelin-1 and big endothelin-1 concentrations returned to normal in both superior vena cava and inferior vena cava. These data indicate that the endothelial system involvement for the two venous beds is different and suggest that local rather than systemic evaluation could better explain endothelial involvement and the contribution of different anatomic sites to the biosynthesis, conversion and clearance of the various involved molecules.

Inspired oxygen fraction after cardiopulmonary bypass: effects on pulmonary function with regard to endothelin-1 concentrations and venous admixture

Twenty consecutive patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) were allocated at random to group 1 (n = 10, high inspired oxygen fraction (FIO2) after CPB), or group 2 (n = 10, moderate FIO2 after CPB). The effects of each FIO2 on arterial and mixed venous concentrations of endothelin-1 (ET-1) and its precursor, Big ET-1, were measured. Venous admixture was calculated to assess the efficiency of pulmonary gas exchange. Patients whose lungs had been ventilated with a FIO2 of 1.0 (exposure time 70 min) after weaning from the CPB machine had significantly greater arterial and mixed venous Big ET-1 concentrations and venous admixture than patients whose lungs were ventilated with a FIO2 of 0.35. In contrast, ET-1 concentrations in the two groups were not significantly different. A reduction of FIO2 from 1.0 to 0.6 reduced venous admixture without lowering endothelial peptide concentrations. On the first postoperative day all peptide concentrations were similar in the two groups, whereas venous admixture remained non-significantly higher in group 1. A short period of high FIO2 immediately after CPB increases endothelin concentrations and pulmonary venous admixture.

Perioperative plasma endothelin-1 and Big endothelin-1 concentrations in elderly patients undergoing major surgical procedures.

Plasma concentrations of the vasoconstrictor endothelin-1 (ET-1) increase during acute physiologic stress, but the role of ET-1 in the pathophysiology of stress remains largely undefined. Whether ET-1 mediates thermoregulatory changes in vasomotor tone is unknown. ET-1 and its more stable precursor, Big ET-1, were measured in plasma obtained at several perioperative time points from 95 consecutive elderly patients (mean age 70 +/- 1 yr) randomized to receive either normothermic or hypothermic perioperative care while undergoing major surgical procedures. In the postoperative period, there were no significant changes in plasma ET-1 concentrations, but Big ET-1 concentrations increased considerably (P < 0.0001). There were no significant differences in mean ET-1 or Big ET-1 levels in normothermic and hypothermic patients. Preoperative and postoperative ET-1 concentrations were significantly higher in patients with a history of hypertension (P < 0.002) and in those requiring treatment for postoperative hypertension (P < 0.003). Patients with cancer and those undergoing abdominal surgery had significantly higher Big ET-1 concentrations (P < 0.0001 and P < 0.003, respectively). These data support the hypothesis that Big ET-1 is a more sensitive measure of endothelin system activation after major surgery. Premorbid conditions and location and type of surgery influence perioperative ET-1/Big ET-1 concentrations. The endothelin response seems to be significantly associated with perioperative hemodynamic aberrations. The endothelin-1 (ET-1) precursor Big ET-1 is a more sensitive measure of the endothelin system activation in response to surgical stress than ET-1 alone. Thermoregulatory vasoconstriction in response to mild perioperative hypothermia occurs independently of the endothelin system.

Perioperative Plasma Endothelin-1 and Big Endothelin-1 Concentrations in Elderly Patients Undergoing Major Surgical Procedures

Plasma concentrations of the vasoconstrictor endothelin-1 (ET-1) increase during acute physiologic stress, but the role of ET-1 in the pathophysiology of stress remains largely undefined. Whether ET-1 mediates thermoregulatory changes in vasomotor tone is unknown. ET-1 and its more stable precursor, Big ET-1, were measured in plasma obtained at several perioperative time points from 95 consecutive elderly patients (mean age 70 +/- 1 yr) randomized to receive either normothermic or hypothermic perioperative care while undergoing major surgical procedures. In the postoperative period, there were no significant changes in plasma ET-1 concentrations, but Big ET-1 concentrations increased considerably (P < 0.0001). There were no significant differences in mean ET-1 or Big ET-1 levels in normothermic and hypothermic patients. Preoperative and postoperative ET-1 concentrations were significantly higher in patients with a history of hypertension (P < 0.002) and in those requiring treatment for postoperative hypertension (P < 0.003). Patients with cancer and those undergoing abdominal surgery had significantly higher Big ET-1 concentrations (P < 0.0001 and P < 0.003, respectively). These data support the hypothesis that Big ET-1 is a more sensitive measure of endothelin system activation after major surgery. Premorbid conditions and location and type of surgery influence perioperative ET-1/Big ET-1 concentrations.The endothelin response seems to be significantly associated with perioperative hemodynamic aberrations. The endothelin-1 (ET-1) precursor Big ET-1 is a more sensitive measure of the endothelin system activation in response to surgical stress than ET-1 alone. Thermoregulatory vasoconstriction in response to mild perioperative hypothermia occurs independently of the endothelin system.

Direct enzyme immunometric measurement of plasma big endothelin-1 concentrations and correlation with indicators of left ventricular function

Recent studies have suggested that the plasma concentrations of endothelin-1, a potent vasoconstrictive peptide, are increased in patients with congestive heart failure. This study aimed to evaluate a new direct ELISA for big endothelin-1 (the precursor of endothelin-1), in comparison with a big endothelin-1 ELISA using plasma sample extraction, and to investigate whether plasma big endothelin-1 concentrations correlate with indicators of left ventricular function. The direct ELISA yielded significantly (P < 0.001) lower results than the assay with extracted samples (0.9 +/- 0.5 pmol/L vs 2.7 +/- 1.9 pmol/L; n = 90); however, the results of the two assays were closely correlated (r = 0.86, P < 0.001). Plasma big endothelin-1 concentrations exhibited a significant (P < 0.001) negative correlation (r = -0.46, r = -0.40) with the left ventricular ejection fraction and a significant positive correlation (r = 0.40, P < 0.001; r = 0.36, P < 0.01) with the left ventricular end-diastolic pressure and the left ventricular end-diastolic (r = 0.42, r = 0.38, P < 0.001) and end-systolic (r = 0.52, r = 0.47, P < 0.001) volume indices. Plasma big endothelin-1 concentrations were notably greater in patients with New York Heart Association (NYHA) class II-IV symptoms than in patients without cardiac disease or in patients categorized to NYHA class I. These data suggest that plasma big endothelin-1 concentrations, measured by a direct ELISA, correlate with hemodynamic indicators and symptoms of left ventricular dysfunction.

Endothelin-1 secretion by alveolar macrophages in systemic sclerosis.

Endothelin-1 (ET-1), a potent fibroblast/smooth muscle cells mitogen, has been implicated in the pathogenesis of systemic sclerosis lung disease (SSc). Since monocytes and macrophages are thought to be activated in SSc, we hypothesized that alveolar macrophages (AM) and their precursors blood monocytes from patients with SSc produced more ET-1 than cells from healthy subjects. ET-1 and big ET-1 concentrations were measured in plasma, in bronchoalveolar lavage (BAL) fluids and in cell culture supernatants from monocytes and alveolar macrophages derived from 13 patients with definite SSc with lung involvement and from 10 control subjects. Plasma and BAL fluid ET-1 and big ET-1 levels were similar in both controls and patients with SSc. ET-1 and big ET-1 concentrations in unstimulated alveolar macrophage supernatants were similar in both groups. In contrast, LPS-stimulated alveolar macrophages from patients with SSc secreted higher amounts of ET-1 and big ET-1 than control subjects. ET-1 and big ET-1 concentrations in monocyte supernatants (either LPS-stimulated or not) were not different in patients and controls. These results show that AM from patients with SSc are hyperresponsive to LPS in vitro in terms of ET-1 and big ET-1 production and suggest that AM could participate in vivo in the overproduction of this potentially profibrotic mediator in patients with SSc.

Sandwich-type enzyme immunoassay for big endothelin-1 in plasma: concentrations in healthy human subjects unaffected by sex or posture

A sandwich-type enzyme immunoassay has been developed for measuring human big endothelin-1 (big ET-1) in human plasma and supernatant fluids from human cell cultures. Big ET-1 is the precursor of endothelin 1 (ET-1), the most potent vasoconstrictor known. A rabbit antibody raised against the big ET-1 COOH-terminus fragment was used as an immobilized antibody (anti-P16). The Fab' fragment of a monoclonal antibody (1B3) raised against the ET-1 loop fragment was used as the enzyme-labeled antibody, after being coupled to acetylcholinesterase. The lowest detectable value in the assay was 1.2 pg/mL (0.12 pg/well). The assay was highly specific for big ET-1, demonstrating no cross-reactivity with ET-1, <0.4% cross-reactivity with big endothelin-2 (big ET-2), and <0.1% with big endothelin-3 (big ET-3). We used this assay to evaluate the effect of two different postural positions (supine and standing) on plasma big ET-1 concentrations in 11 male and 11 female healthy subjects. Data analysis revealed that neither sex nor body position influenced plasma big ET-1 concentrations. This assay should thus permit the detection of possible variations in plasma concentrations of big ET-1 in certain pathologies and, in association with ET-1 assay, make possible in vitro study of endothelin-converting enzyme activity in cell models. Such studies could clarify the physiological and clinical roles of this family of peptides.

Endothelin-1 and big endothelin-1 levels in normal term pregnancy and in preeclampsia

To study the concentrations of endothelin-1 (ET-1) and its precursor, big ET-1, in samples of amniotic fluid, fetal urine, umbilical arterial and venous blood, retroplacental blood and maternal uterine and brachial venous blood obtained from normal and preeclamptic women. Samples were collected from 31 healthy pregnant women (16 in labor and 15 undergoing elective cesarean section) and 35 preeclamptic women (9 in labor and 26 undergoing cesarean section). Big ET-1 and ET-1 were measured by radioimmunoassay and the ET-1 to big ET-1 ratios were calculated. In preeclamptic women there was a significant elevation of ET-1 in the maternal brachial and uterine veins and of big-ET-1 in the brachial vein. The ET-1 concentrations and the ET-1/big ET ratios were significantly higher on the fetal side (i.e., in the umbilical vein and amniotic fluid) than in maternal blood, but in these sampling locations there was no difference between the normal pregnancy and preeclampsia group. A significant negative correlation ( r = −0.67, P < 0.01) was found between plasma ET-1 in the umbilical vein and birth weight in the preeclamptic group. ET-1 was significantly higher in amniotic fluid than in the first neonatal urine of corresponding pregnancies (15.0 ± 2.0 vs. 8.0 ± 2.9 pmol/l, P < 0.05). The ET-1 and big ET-1 concentrations are significantly higher in fetal plasma and amniotic fluid than in maternal plasma, indicating increased endothelin converting enzyme activity and increased ET-1 production in utero. The elevated ET-1 concentration in maternal blood in preeclamptic compared with normal pregnant women and the negative correlation between ET-1 in the umbilical vein and birth weight suggest that ET-1 plays a pathophysiological role in preeclampsia and other conditions with intrauterine growth restriction.

Changes in plasma endothelin-1 and Big endothelin-1 induced by transjugular intrahepatic portosystemic shunts in patients with cirrhosis and refractory ascites

Background/Aims: Endothelin-1 (ET-1) is a potent vasoconstrictor that may be involved in the pathogenesis of splanchnic and renal hemodynamic changes associated with portal hypertension. The aim of this study was to measure the concentration of ET-1 and of its precursor Big endothelin-1 (Big ET-1) in the systemic circulation as well as in the splanchnic and renal venous beds and to evaluate changes after the relief of portal hypertension following transjugular intraheptic portosystemic shunt placement. Methods: Plasma concentrations of ET-1 and of Big ET-1 were measured in the vena cava, renal vein, hepatic vein and portal vein in ten patients with cirrhosis and refractory ascites before and 1–2 months after transjugular intrahepatic portosystemic shunt. The porto-caval gradient, creatinine clearance, plasma aldosterone and renin activity, as well as daily urinary sodium excretion were measured at the same time. Results: The plasma concentration of ET-1 and Big ET-1, respectively, in peripheral blood of normal volunteers were 0.28±03 and 3.95±0.34 pg/ml; the concentrations of both peptides were higher in patients with cirrhosis, both in vena cava (0.61±0.14 and 10.01±1.47 pg/ml), hepatic vein (0.62±0.13 and 13.93±1.77 pg/ml), portal vein (1.21±0.12 and 17.84±1.98 pg/ml) and renal vein (0.76±0.12 and 14.21±1.55 pg/ml). Moreover ET-1 and Big ET-1 concentrations were more elevated in the portal vein that in the vena cava (+98% and +70%) and slightly higher in the renal vein as compared to the vena cava (+25% and +42%). After transjugular intrahepatic portosystemic shunt, a rise in creatinine clearance and urinary sodium excretion (+49%; and +53%) was observed together with a marked reduction in plasma aldosterone and renin activity (−59% and −49%). ET-1 and Big ET-1 concentrations remained unchanged in the vena cava whereas a significant reduction of ET-1 and Big ET-1 occured both in the portal vein (−43% and − 44%) and in the renal vein (−53% and −29%). Portal vein and renal vein concentrations of both peptides became similar to vena cava levels. Conclusions: Splanchnic and renal hemodynamic changes occurring in patients with cirrhosis and refractory ascites could be related to the production of ET-1 by splanchnic and renal vascular beds. This was abolished by transjugular intrahepatic portosystemic shunt, which could explain the exacerbation of systemic vasodilation and the improvement in renal perfusion observed after the procedure.

Changes in cerebrospinal fluid and cerebrovascular endothelin concentrations during hypotension and hypertension in newborn piglets with induced sterile meningitis

The effects of sterile meningitis on endothelin-1 (ET-1) and big ET-1 concentrations during hypotension and hypertension were studied in the cerebrospinal fluid and plasma of newborn piglets. Cerebrospinal fluid was obtained via cisterna magna puncture, and blood was obtained from the sagittal sinus vein and left subclavian artery. The study group consisted of 14 newborn piglets injected with 0.5 mL heat-killed group B streptococcus (GBS) (10(9) colony forming unit (cfu) equivalents), into the right cerebral lateral ventricle; the control group consisted of 10 newborn piglets injected with sterile normal saline, in a similar fashion. Hypotension (mean arterial blood pressure (MABP) 20-59 mmHg; 1 mmHg = 133.3 Pa) and hypertension (MABP 110-140 mmHg) were induced 1.5-2 h apart in random sequence in each animal, by inflating balloon-tipped catheters placed at the aortic root and descending aorta, respectively. Cerebral blood flow (CBF) was measured using radiolabeled microspheres, 15 min before and after injection of GBS or saline (normotension), during the hypotension and hypertension episodes, and during recovery normotension, immediately prior to cerebrospinal fluid and blood sampling. ET-1 and big ET-1 concentrations (pg/mL) were measured using radioimmunoassay kits. The combined effect of induced sterile meningitis and induced hypotension resulted in a significant rise in the concentration of cerebrospinal fluid ET-1 (control, 5.1 +/- 0.1; GBS, 9.3 +/- 0.2 pg/mL; p < 0.01), cerebrospinal fluid big ET-1 (control, 0; GBS, 18.1 +/- 2.7 pg/mL; p < 0.01), and sagittal sinus (cerebrovascular) big ET-1 (control, 15.5 +/- 4.2; GBS, 47.5 +/- 9.6 pg/mL; p < 0.01). In contrast, the combined effect of induced sterile meningitis and induced hypertension resulted in a marked elevation in cerebrovascular ET-1 concentrations (control, 9.5 +/- 0.9; GBS, 28.5 +/- 6.1 pg/mL; p < 0.01), with no significant change in cerebrospinal fluid concentrations. In addition, cerebrovascular production of ET-1 increased dramatically during hypertension in the GBS group (control, 0; GBS, 161.7 +/- 13.2 pg.min-1.100 g-1; p < 0.001), and was maintained during the recovery period (133.7 +/- 10.8 pg.min-1.100 g-1). Cerebrovascular ET-1 concentrations correlated significantly with total CBF and MABP in both groups of animals (control, r = 0.49, p < 0.002; GBS, r = 0.64, p < 0.0001), but the response was of a much greater magnitude in the GBS group. There was an inverse relationship between cerebrovascular big ET-1 concentrations and total CBF (r = -0.53, p < 0.0001) and MABP (r = -0.71, p < 0.0001) in the GBS group. In the MABP range of 60-110 mmHg a positive relationship was observed between cerebrovascular ET-1 concentrations and cerebral vascular resistance, in the control group only (r = 0.59, p < 0.002). The combined insult of induced sterile meningitis and induced hypotension or hypertension may be associated with increased cerebrovascular ET-1 and (or) big ET-1 concentrations. Changes in these vasoactive agents may contribute to pressure passivity of CBF in the newborn with meningitis.