Vasoconstrictor activity of novel endothelin peptide, ET-1(1 - 31), in human mammary and coronary arteries in vitro.

1. The ability of the putative chymase product of big endothelin-1 (big ET-1), ET-1(1 - 31), to constrict isolated endothelium-denuded preparations of human coronary and internal mammary artery was determined. 2. pD2 values in coronary and mammary artery respectively were 8.21+/-0.12 (n=14) and 8.55+/-0.11 (n=12) for ET-1, 6.74+/-0.11 (n=16) and 7.10+/-0.08 (n=16) for ET-1(1 - 31) and 6.92+/-0.10 (n=15) and 7.23+/-0.11 (n=12) for big ET-1. ET-1(1 - 31) was significantly less potent than ET-1 (P<0.001, Student's t-test) and equipotent with big ET-1. 3. Vasoconstrictor responses to 100 - 700 nM ET-1(1 - 31) were significantly (P<0.05, Student's paired t-test) attenuated by the ET(A) antagonist PD156707 (100 nM). 4. There was no effect of the ECE inhibitor PD159790 (30 microM), the ECE/NEP inhibitor phosphoramidon (100 microM) or the serine protease inhibitor chymostatin (100 microM) on ET-1(1 - 31) responses in either artery. 5. Radioimmunoassay detected significant levels of mature ET in the bathing medium of coronary (1.6+/-0.5 nM, n=14) and mammary (2.1+/-0.6 nM, n=14) arteries, suggesting that conversion of ET-1(1 - 31) to ET-1 contributed to the observed vasoconstriction. 6. ET-1(1 - 31) competed for specific [(125)I]-ET-1 binding to ET(A) and ET(B) receptors in human left ventricle with a pooled K(D) of 71.6+/-7.0 nM (n=3). 7. Therefore, in human arteries the novel peptide ET-1(1 - 31) mediated vasoconstriction via activation of the ET(A) receptor. The conversion of ET-1(1 - 31) to ET-1, by an as yet unidentified protease, must contribute wholly or partly to the observed constrictor response. Chymase generated ET-1(1 - 31) may therefore represent an alternative precursor for ET-1 production in the human vasculature.     

Contractile activity of three endothelins (ET-1, ET-2 and ET-3) on the human isolated bronchus.

1. The effects of three endothelins: (i) the classical or human/porcine endothelin (ET-1); (ii) [Trp6, Leu7] endothelin (ET-2) and (iii) [Thr2, Phe4, Thr5, Tyr6, Lys7, Tyr14] endothelin or rat endothelin (ET-3) were tested on the human isolated bronchus. 2. ET-1 produced a concentration-dependent contraction of the human isolated bronchus that proceeded in two different steps. The first step was observed at very low concentrations (pD2 = 11.01 +/- 0.17, n = 10) but corresponded to a low intrinsic activity (Emax = 15.6 +/- 1.8% of Emax = 26.1 +/- 2.9% of ACh 3 x 10(-3) M, n = 5, P less than 0.05), reduced by nicardipine 10(-6) M (Emax = 6.0 +/- 2.6% of ACh 3 x 10(-3) M, n = 5, P less than 0.05) and strongly inhibited in calcium-free medium. The second step of the action of ET-1 corresponded to a lesser potency (pD2 = 7.90 +/- 0.17, n = 9) but a higher intrinsic activity (Emax = 82.5 +/- 4.7% of ACh 3 x 10(-3) M). This effect was not significantly modified by nicardipine 10(-6) M or by Bay K 8644 10(-7) M. Neither of the two effects was modified by indomethacin 3 x 10(-6) M. 3. The effects of ET-2 and ET-3 were qualitatively similar to those of ET-1 but quantitatively different; for these two steps of contracting activity and for potency and efficacy the ranking was: ET-1 greater than ET-2 = ET-3.(ABSTRACT TRUNCATED AT 250 WORDS)     

Glucose-mediated transforming growth factor-beta1 release in human mesothelial cells is endothelin independent

Glucose and mechanical forces have been shown to be potent stimuli for mesothelial endothelin-1 release promoting profibrotic processes during peritoneal dialysis. We studied the osmolarity-induced and physical stress-induced effects on transforming growth factor-beta1 (TGF-beta1) release in human peritoneal mesothelial cells (HPMC), and analyzed whether a combined endothelin-A/endothelin-B receptor antagonist is able to mitigate HPMC TGF-beta1 release. D-Glucose and glycerol were used to analyze the impact of osmolarity on HPMC TGF-beta1 release. A cellular model of non-laminar fluid shear stress and cellular stretch was used to analyze the effects of physical forces. To neutralize the endothelin effects, a combined endothelin-A/endothelin-B receptor antagonist (LU 302 872) was chosen. Glucose, but not glycerol, increased mesothelial TGF-beta1 release in a concentration-dependent and time-dependent manner (P < 0.05 versus controls). Mechanical forces alone had no effect on mesothelial TGF-beta release. Combining fluid shear stress with high glucose medium led to a 30% increase (P = 0.019), and cellular stretch to a 34% increase (P = 0.075) in TGF-beta release compared with glucose stress alone. The combined endothelin-A/endothelin-B receptor antagonist had no impact on the mesothelial TGF-beta release. In conclusion, HPMC TGF-beta1 release by glucose and mechanical stress seems not to be related to the activity of the peritoneal endothelin system - at least in our in vitro model.     

Inhibition of histamine release and pressure increase induced by endothelin (ET-1) in isolated rat kidneys treated with propionyl carnitine.

Endothelin-1 (ET-1) is an amino peptide produced by endothelial cells with a potent vasoconstrictor activity; this effect is regulated by a release of other endogenous vasal factors. Recent studies have demonstrated that endothelin is capable of releasing from different tissues, and particularly from perfused organs such as spleen and kidney, many vasal factors and prostanoids. The present study investigates whether perfusion with a solution of endothelin-1 in rat isolated kidney can induce the release of histamine, another vasal factor (until now not investigated in relation with endothelin-1) and whether treatment with propionyl carnitine, a compound with vasoprotecting activity, inhibits this release. This research demonstrates that histamine released by rat kidney perfused with endothelin is lowered if previously treated with propionyl carnitine. This effect of propionyl carnitine can be considered to be another important factor in a complex mechanism involved in its vasoprotective and cardiovascular action.     

地塞米松抑制慢性心衰大鼠心肌中内皮素信号通路的过度激活而改善心肌纤维化

目的：观察地塞米松对慢性心衰大鼠心肌中内皮素（ET）信号通路的过度激活与氧化应激的干预作用。方法：雄性SD大鼠,通过冠脉结扎6周造成慢性心衰模型。分为慢性心衰组、地塞米松组,另设假手术组作为阴性对照。地塞米松组动物在饮水中按1μg/mL的浓度给予地塞米松治疗。连续治疗6周后,取心脏进行Masson三色法染色,以检测心肌纤维化;RT-PCR法检测心肌组织中ETA受体、NF-κB和一氧化氮合酶（iNOS）的基因表达水平。结果：与假手术组相比,慢性心衰组大鼠心肌纤维化显著,地塞米松能有效改善心衰大鼠心肌组织的纤维化;心衰大鼠心肌组织中ETA受体、NF-κB和iNOS的基因表达水平明显上调,而地塞米松可使心衰大鼠心肌中ETA受体、NF-κB和iNOS的基因表达水平显著下调。结论：地塞米松通过下调ETA受体,抑制ET信号通路的过度激活和抗氧化作用,有效改善慢性心衰大鼠的心肌纤维化。     

吲达帕胺对高血压病人血浆内皮素-1的影响

目的　研究轻、中度原发性高血压病人的血浆内皮素 1(ET 1)的变化及其在原发性高血压发生及发展中的作用 ,评价吲达帕胺对轻、中度原发性高血压的降压疗效及对这类病人血浆ET 1水平的影响 ,探讨吲达帕胺对高血压的影响机制。方法　将 30例轻、中度原发高血压病人和 30例正常人的血浆采用放射免疫法测定血浆ET 1水平 ,对高血压病人给予吲达帕胺治疗 2周 ,并进行治疗前后对照研究。结果　高血压组治疗后血压明显下降 ,平均舒张压降低 9 8mmHg ,P <0 0 1,降压有效率为 6 0 %。高血压组治疗前血浆ET 1较正常组显着升高 ,平均升高 34 5 5 3pg/L ,P <0 0 0 1,治疗后ET 1水平显着下降 ,平均降低 35 5 5 0pg/L ,P <0 0 0 1。结论　原发性高血压病人血浆ET 1较正常人高 ,这类人群存在内皮细胞分泌活动的紊乱 ,是原发性高血压疾病发展的重要环节。吲达帕胺 (2 5mg/d)对轻、中度原发高血压病人降压疗效显著 ,同时可降低血浆ET 1水平 ,从而可抑制内素促进高血压进展的作用。     

The endothelin system in human saphenous vein graft disease.

Saphenous vein graft stenosis is a significant clinical complication for coronary artery bypass patients. Endothelin-1, a peptide synthesised by vascular endothelial cells, is the most potent known vasoconstrictor and has mitogenic properties. Recent advances in our knowledge of endothelin-1 synthesis and endothelin receptor expression and function in normal and atherosclerotic human saphenous vein imply a role for the peptide in the progression of vein graft failure. Manipulation of the endothelin system, by selective receptor antagonism or inhibition of the specific endothelin-converting enzymes may, therefore, represent a novel therapeutic target for treating vein graft disease.     

Nephrotoxicants induce endothelin release and signaling in renal proximal tubules: effect on drug efflux

We previously used killifish proximal tubules, fluorescent substrates, and confocal microscopy to demonstrate that transport mediated by the multidrug resistance protein (Mrp2) and by P-glycoprotein was reduced by nanomolar concentrations of endothelin-1 (ET), acting through a basolateral B-type ET receptor and protein kinase C (PKC). Here we show that representatives of two classes of nephrotoxicants decrease transport by activating the endothelin-PKC signaling pathway. Exposing tubules to radiocontrast agents (iohexol, diatrizoate) or aminoglycoside antibiotics (gentamicin, amikacin) reduced Mrp2-mediated fluorescein methotrexate (FL-MTX) transport from cell to tubular lumen. Pretreating the tubules with an ET(B)-receptor antagonist or with PKC-selective inhibitors abolished these effects. The nephrotoxicants activated signaling by inducing release of ET from the tubules, because adding of an antibody against ET to the medium abolished the effects. Elevating medium Ca(2+) also reduced FL-MTX transport; this reduction was abolished when tubules were pretreated with an ET antibody, an ET(B)-receptor antagonist, PKC-selective inhibitors, or the Ca(2+) channel blocker, nifedipine. None of these drugs by themselves affected FL-MTX transport. Importantly, nifedipine also blocked the ET(B)-receptor/PKC-dependent reduction in FL-MTX transport caused by gentamicin and diatrizoate. These results for two classes of structurally unrelated nephrotoxicants suggest that Ca(2+)-dependent ET release and subsequent action through an autocrine mechanism may be an early response to tubular injury.     

血清内皮素、单核细胞趋化蛋白和基质金属蛋白酶-9水平与冠心病的关系研究

目的探讨血清内皮素（ET-1）、单核细胞趋化蛋白（MCP-1）和基质金属蛋白酶-9（MMP-9）水平与不同类型冠心病的关系。方法80例冠心病患者,按不同类型分为急性心肌梗死（AMI）组22例、不稳定型心绞痛（UAP）组33例、稳定型心绞痛（SAP）组25例,另选择30例健康体检者作为对照组。采用ELISA法检测血清ET-1、MCP-1和MMP-9的水平,比较各组间的差异。结果四组血清ET-1（F=17．36）、MCP-1（F=13．51）和MMP-9（F=15．43）水平差异均有统计学意义（均P〈0．05）。组间比较：AMI组、UAP组及SAP组较对照组高（t=5．12、5．35、5．15、4．22、4．65、4．54、3．12、3．65、3．54,均P〈0．05）;AMI组、UAP组较SAP组高（t=4．32、4．15、4．52、3．54、3．23、3．51,均P〈0．05）;AMI组较UAP组高（t=3．78、3．96、3．56,均P〈0．05）。结论血清ET-1、MCP-1和MMP-9可能是冠状动脉粥样硬化的标志,参与了冠心病的发病机制,与冠状动脉病变程度密切相关。     

Effects of selective and non-selective endothelin receptor blockade on ET-1-induced pressor response in the hamster

In order to assess the physiological balance existing between vasoconstrictor and vasodilator endothelin-B receptor actions associated with their dual locations (i.e. on vascular smooth muscle and endothelial cells), we investigated the effects of selective and non-selective endothelin receptor antagonists on endothelin-1-induced increase in blood pressure. Atrasentan (a selective endothelin-A receptor antagonist; 6 mg/kg) and A-192621 (a selective endothelin-B receptor antagonist; 0.03, 0.3, or 30 mg/kg) were administered intravenously to anaesthetized Syrian Golden hamsters, alone or in combination, to induce respectively selective or non-selective receptor antagonism. Atrasentan partially blocked the blood pressure response induced by endothelin-1 (0.5 nmol/kg), whereas a selective endothelin-B receptor antagonism potentiated this response, independently of the dose of A-192621. Interestingly, combination of the very low dose of A-192621 (which selectively blocked putatively endothelium-located endothelin-B receptors) with atrasentan, suppressed the protective effect previously observed with atrasentan alone. Nevertheless, combination of atrasentan with the two highest doses of A-192621 tested, dose-dependently reduced the response triggered by endothelin-1. Our results suggest that endothelial endothelin-B receptors are important to control the vascular reactivity to endothelin-1. Furthermore, our data suggest that the efficacy of a non-selective endothelin-A/ endothelin-B receptor antagonist relies upon its potency to block endothelin-B receptors in the hamster.     

重组人脑钠肽对急性心衰犬血管紧张素Ⅱ和内皮素-1的影响

目的研究重组人脑钠肽(rhBNP)对普萘洛尔诱导比格犬急性心力衰竭后血浆血管紧张素Ⅱ(AngⅡ)、内皮素-1(ET-1)、尿量、尿钠、尿钾及血钠、血钾含量的影响。方法静脉推注普萘洛尔诱导急性心力衰竭,静脉滴注普萘洛尔维持心衰,股动脉插管监测血流动力学指标变化,电磁流量计测量心输出量,输尿管插管测量尿量,模块式全自动生化仪测定尿钠、尿钾、血钠和血钾含量,放免法测定血浆AngⅡ和ET-1的含量。结果心衰犬静脉滴注重组人脑钠肽后,AngⅡ和ET-1的含量较基础值降低(P<0.05~0.01),尿量、尿钠明显增加(P<0.05),尿钾含量减少(P<0.05~0.01)。结论rhBNP降低普萘洛尔所致比格犬急性心力衰竭血浆AngⅡ和ET-1的浓度,并具有明显的利钠利尿的作用,对急性心衰产生保护作用。     

Functional and biochemical evidence for capsaicin-induced neural endothelin release in isolated working rat heart.

In isolated working rat heart, capsaicin elicited a concentration-dependent constriction of coronary arteries accompanied by decline of all cardiac parameters recorded (heart rate, coronary and aortic flow, left ventricular developed pressure, and first derivative of left ventricular developed pressure). The following evidence suggests that capsaicin-induced changes are mediated by endothelin of neural origin: (1) the capsaicin (10 nM)-evoked decrease in coronary flow resulting in deterioration of cardiac functions was mimicked by endothelin (0.1 nM); (2) the selective endothelin ET(A) receptor antagonist, cyclo (D-alpha-aspartyl-L-propyl-D-valyl-L-leucyl-D-tryptophyl) (1 microM), abolished the cardiac effects provoked by capsaicin (10 nM); (3) reduction of extracellular Ca2+ concentration from 2.4 to 1.2 or 0.6 mM inhibited the cardiac effects of capsaicin (10 nM) but not those induced by endothelin (0.1 nM); (4) perfusion of the heart with 0.1% (v/v) Triton X-100 damaged the endothelium and reversed the enhancement of coronary flow evoked by bethanechol (1 microM), decreased the basal flow, but was without effect on capsaicin-induced coronary constriction; (5) in response to capsaicin challenge (10-100 nM), the endothelin concentration measured in coronary effluent by means of radioimmunoassay increased up to sevenfold but remained unchanged in the presence of 0.6 mM Ca2+; (6) no reduction of coronary flow was induced by capsaicin (100 nM) applied to the heart of rats which were desensitised by capsaicin (150 mg/kg). It is concluded that, in the rat heart, capsaicin acting on VR1 capsaicin receptors elicits a release of endothelin from the sensory nerve terminals.     

Increased vascular angiotensin II binding capacity and ET-1 release in young cardiomyopathic hamsters

Heart failure (HF) is a multifactorial and progressive disease that has been associated with multiple systemic and vascular alterations. Previous reports from our laboratory showed that in 2-month-old Bio-To2 Syrian cardiomyopathic hamsters (SCH) that have not yet developed the clinical manifestations of HF, the vascular contractility induced by 0.1 microM angiotensin II was approximately 35% greater than in control animals. This finding was observed concomitantly with an increased aortic ACE activity. To further evaluate the mechanisms underlying angiotensin II-enhanced vascular contraction, concentration-response curves for angiotensin II (0.01 nM-10 microM) were constructed before and after the addition of prazosin (alpha-1 blocker), NS-398 (selective COX-2 blocker) and BQ-123 (ET-1A-receptor antagonist) in aortic rings from 2-month-old SCH. The binding capacity and affinity of the AT-1 receptors were also evaluated in aortic homogenates using 125I-angiotensin II. Age-matched golden hamsters were used as controls (CT). Our results indicate that incubation with either 10 microM prazosin or 10 microM NS-398 did not modify EC50 or Emax values for angiotensin II indicating that norepinephrine and prostaglandins are not involved in the enhanced contractile action of angiotensin II. However, 10 microM BQ-123 reduced by 40% the contraction induced by 1.0 microM angiotensin II (from 1.05+/-0.04 to 0.6475+/-0.06 g/mg tissue, n = 5, P < 0.05), suggesting that in cardiomyopathic hamsters, the action of angiotensin II is mediated in part by ET-1. At lower angiotensin II concentration (0.1 microM), the ET-1-dependent contraction decreases to 29%. In addition, although dissociation constants for labeled angiotensin II were found to be similar in the aorta of SCH and control animals (K(D): CT = 7.8 nM and SCH = 5.1 nM), 125I-angiotensin II binding capacity was about 2-fold greater in SCH than in controls (Bmax: SCH = 1113 and CT = 605 fmol/mg protein). Altogether these results suggest that in 2-month-old SCH the enhanced response of angiotensin II in the vasculature is mediated both by an increased binding capacity for the hormone and facilitation of the ET-1 action.     

Effect of endothelin (ET)-1, ET-3 and ET-(16-21) on the isolated and perfused rat kidney from normotensive and spontaneously hypertensive rats.

We have investigated the effect of endothelin (ET)-1, ET-3 and ET-(16-21) on isolated and perfused rat kidney (IPK). ET-1 and ET-3 produced a similar dose-dependent increase in perfusion pressure of IPK, while ET-(16-21) was completely inactive. The ET-1 effects were greater in spontaneously hypertensive rats (SHR) as compared to normotensive rats (WKYR), whereas the ET-3 effects were greater in the SHR group only at the lowest doses. The pressure response of IPK induced by ET-1 was partially modified by prior application of the nitric oxide synthetase inhibitor L-nitroarginine in both WKYR and SHR.     

正常中国人心脏各部位内皮素受体及其亚型的分布

目的　了解正常中国人心脏各部位内皮素受体（ETR）及其亚型的分布。方法　125I-ET-1作为放射配基用放射受体分析法检测心肌细胞膜ETR及其亚型的变化。结果　正常人心脏各部位ETR数目不同,依序为右房≈左房＞室间隔＞右室＞左室;亚型ET     

有氧运动对慢性心力衰竭患者心肌损伤及血浆CGRP和ET-1的影响

目的探讨老年慢性心力衰竭患者有氧运动训练前后血浆内皮缩血管肽（ET-1）和降钙素基因相关肽（CGRP）变化及其与心肌损伤的关系。方法38例NYHA心功能Ⅱ～Ⅲ级的老年住院患者,在常规药物治疗基础上分为对照组18例,采用常规治疗加休息;治疗组20例采用常规治疗加运动组,进行有氧运动训练12周,测定训练前后患者运动耐力和血浆ET-1、CGRP水平并分析其与心肌损伤的关系。结果老年CHF患者治疗前血浆ET-1、CGRP显著高于正常对照组（P〈0.05）;12周治疗后2组CHF患者血浆CK-MB、ET-1和CGRP降低（P〈0.05）,常规治疗加运动组降低更加显著具有统计学意义。结论老年心力衰竭患者ET-1、CGRP分泌失调,可能参与心肌损伤过程,有氧运动训练能降低血浆ET-1、CGRP水平减轻心肌损伤。     

氨茶碱对支气管哮喘气道重塑大鼠支气管肺组织内皮素-1和一氧化氮含量的影响

目的观察氨茶碱对支气管哮喘气道重塑大鼠气道形态学及肺组织中内皮素-1（ET-1）、一氧化氮（NO）、11型胶原含量的影响。方法24只SD大鼠随机分为正常组、模型组、治疗组,每组8只,除正常组外以卵蛋白致敏并吸入激发法制备大鼠哮喘模型,治疗组、模型组从第1次哮喘激发开始（造模第15天）分别给予氨茶碱35mg·kg^-1·次^-1·d^-1、0．9％氯化钠溶液2ml·次^-1·d^-1灌胃给药,用药4周后处死大鼠,取肺组织HE染色,病理图象分析仪测量支气管壁面积、支气管平滑肌面积,采用放射免疫法测定肺组织ET-1、Ⅲ型胶原含量,采用硝酸还原酶法测定肺组织NO含量。结果与正常组比较,模型组大鼠支气管壁面积、平滑肌面积明显增加（P〈0．01）,肺组织中ET-1、NO、II型胶原含量均明显增加（P〈0．01）;与模型组比较,治疗组大鼠支气管壁面积、平滑肌面积较模型组显著降低（P〈0．01）,肺组织中ET-1、NO、11型胶原含量均显著降低（P〈0．05或〈0．01）结论氨茶碱可通过降低肺组织中ET—1、NO、Ⅲ型胶原含量,抑制哮喘大鼠气道壁、平滑肌增厚,从而抑制支气管哮喘大鼠气道重塑。