Effects of PEAR1 gene polymorphism on big endothelin-1 levels in Chinese patients with acute myocardial infarction after percutaneous coronary intervention

Acute myocardial infarction (AMI) has been associated with poor prognosis,even after revascularization with percutaneous coronary intervention (PCI),likely due to coronary endothelial cell dysfunction and injury.^([1,2])Endothelin-1 (ET-1),a peptide that serves as a vasoconstrictor of smooth muscle cell proliferation,can reflect endothelial cell functional states.Due to low circulation levels and short plasma half-life time,measuring plasma ET-1 levels is difficult.In contrast,big ET-1.

Engineered SPIONs functionalized with endothelin a receptor antagonist ameliorate liver fibrosis by inhibiting hepatic stellate cell activation

Endothelin-1/endothelin A receptor(ET-1/ETAR)pathway plays an important role in the progression of liver fibrosis by activating hepatic stellate cells(HSCs)-a key cell type involved in the pathogenesis of liver fibrosis.Inactivating HSCs by blocking the ET-1/ETAR pathway using a selective ETAR antagonist(ERA)represents a promising therapeutic approach for liver fibrosis.Unfortunately,small-molecule ERAs possess limited clinical potential due to poor bioavailability,short half-life,and rapid renal clearance.To improve the clinical applicability,we conjugated ERA to superparamagnetic iron-oxide nanoparticles(SPIONs)and investigated the therapeutic efficacy of ERA and ERA-SPIONs in vitro and in vivo and analyzed liver uptake by in vivo and ex vivo magnetic resonance imaging(MRI),HSCs-specific localization,and ET-1/ETAR-pathway antagonism in vivo.In murine and human liver fibrosis/cirrhosis,we observed overexpression of ET-1 and ETAR that correlated with HSC activation,and HSC-specific localization of ETAR.ERA and successfully synthesized ERA-SPIONs demonstrated significant attenuation in TGFβ-induced HSC activation,ECM production,migration,and contractility.In an acute CCl4-induced liver fibrosis mouse model,ERA-SPIONs exhibited higher liver uptake,HSC-specific localization,and ET-1/ETAR pathway antagonism.This resulted in significantly reduced liver-to-body weight ratio,plasma ALT levels,andα-SMA and collagen-I expression,indicating attenuation of liver fibrosis.In conclusion,our study demonstrates that the delivery of ERA using SPIONs enhances the therapeutic efficacy of ERA in vivo.This approach holds promise as a theranostic strategy for the MRI-based diagnosis and treatment of liver fibrosis.

Corrigendum: Astrocytic endothelin-1 overexpression impairs learning and memory ability in ischemic stroke via altered hippocampal neurogenesis and lipid metabolism

In the article titled“Astrocytic endothelin-1 overexpression impairs learning and memory ability in ischemic stroke via altered hippocampal neurogenesis and lipid metabolism,”published on pages 650-656,Issue 3,Volume 19 of Neural Regeneration Research(Li et al.,2024),there were two errors that needed to be corrected.

Endothelin receptor antagonists for the treatment of diabetic nephropathy:A meta-analysis and systematic review

BACKGROUND Diabetic nephropathy(DN)is the main cause of chronic kidney disease and endstage renal disease worldwide.Although available clinical trials have shown that endothelin receptor(ER)antagonists may be a novel and beneficial drug for DN,no consistent conclusions regarding their sufficient effectiveness and safety for patients with DN have been presented.AIM To assess the effectiveness and safety of ER antagonists among patients with DN.METHODS The EMBASE,PubMed,MEDLINE,Cochrane,and ClinicalTrials.gov databases were searched without any language restrictions.Relative risks with 95%confidence intervals(CIs)for dichotomous data and mean differences or standardized mean difference with 95%CIs for continuous data were calculated using Review Manager 5.3 software.Publication bias was assessed using Egger’s test with Stata/SE software.RESULTS We enrolled seven studies with six data sets and 5271 participants.The ER antagonists group showed a significantly greater reduction in albuminuria and more patients with 40%reduction in urinary albumin-to-creatinine ratio than the control group(P<0.0001 and P=0.02,respectively).Subgroup analysis for reductions in estimated glomerular filtration rate(eGFR)showed that for the middle-dosage subgroup,the ER antagonists group exhibited lower eGFR reduction than the control group(P<0.00001;mean difference,0.7095%CI:0.66,0.74).Moreover,significant reductions in systolic and diastolic blood pressure were observed in the invention group.CONCLUSION ER blockades combined with angiotensin converting enzyme inhibitor/angiotensin II type 1 receptor blockers may be an effective treatment to lower blood pressure and reduce proteinuria in DN with declined eGFR.However,attention should be given to adverse events,including cardiac failure,anemia,and hypoglycemia,as well as serious adverse events.

Endothelin-1诱导的大鼠局灶性脑缺血再灌注模型

目的 研究Endothelin 1(ET 1)诱导的大鼠局灶性脑缺血再灌注模型。方法 将ET 1注入大脑中动脉 (MCA)附近 ,ET 1强烈的缩血管作用可使脑血流 (CBF)降低造成缺血性脑损伤 ,采用氢清除法监测缺血过程中大鼠纹状体脑血流的变化 ,于缺血后 6h进行神经功能评分 ,并采用TTC染色法观察脑梗死面积的变化。结果 ET 1可使纹状体血流呈现浓度依赖性的降低 ,10min时CBF降至最低 ,分别为 :ET 130 0 pmol组 (2 7 1± 2 9) %、36 0pmol组 (12 7±2 1) %、4 0 0pmol组 (11 9± 1 8) %、5 0 0 pmol组 (9 5±1 6 ) % ;神经功能评分显示ET 1可造成大鼠不同程度的神经功能损伤 ;MCAO后 2 4h ,脑梗死面积百分率随ET 1浓度的增加而呈上升趋势 ,并显示出良好的浓度依赖关系 :30 0pmol组 (3 9± 0 3) %、36 0 pmol组 (7 4± 0 5 ) %、4 0 0 pmol组 (11 3± 1 3) %、5 0 0 pmol组 (16 2± 1 8) % ;r =0 992 6(P <0 0 5 )。结论 该模型操作简单 ,造成的脑梗死范围稳定、重现性好 。

VEGF、Endostatin、Endothelin-1在大肠腺瘤及大肠癌中的表达及意义

目的探讨大肠腺瘤及大肠癌中血管内皮生长因子(VEGF)、内皮抑素(Endostatin)、内皮素(Endothelin-1)的表达与病理组织学特征的关系以及三者之间的关系及意义,并分析三者在大肠腺瘤癌变过程中的相互作用。方法分别应用聚合酶链式反应PCR法和免疫组织化学SP法,联合检测VEGF、Endostatin、Endothelin-1在20例大肠腺瘤、40例大肠癌及20例正常大肠组织中的表达情况,并分析其与大肠腺癌临床病理特征之间的关系。结果①在正常大肠组织、大肠腺瘤及大肠癌中,VEGF、Endothelin-1的阳性表达率呈依次递增,VEGF、Endothelin-1在大肠腺癌与正常大肠黏膜之间差异有显著性(P<0.01);Endostatin在正常大肠组织、大肠腺瘤及大肠癌中的阳性表达率呈依次递减,在大肠腺癌与正常大肠粘膜之间差异有显著性(P<0.01);②40例大肠腺癌中,VEGF、Endothelin-1的阳性表达率与肿瘤分化程度、浸润深度、淋巴结转移及远处转移密切相关,Dukes C+D期组高于Dukes A+B期组(P<0.05﹚;Endostatin表达与肿瘤分化程度、浸润深度、淋巴结转移及远处转移呈负相关,Dukes C+D期组低于Dukes A+B期组(P<0.05﹚。结论随着大肠癌的发生发展,VEGF、Endothelin-1的阳性表达率依次增加,提示可作为大肠腺癌发生发展的分子标志,二者在大肠腺癌的发生发展过程中可能具有协同促进作用;两者在大肠腺癌中的表达高于大肠腺瘤组,表明两者在腺瘤向腺癌转变的部分分子机制中起着重要作用。随着大肠腺癌的发生发展,Endostatin的表达逐渐降低,腺癌组低于腺瘤组,提示Endostatin在大肠癌的发生发展、腺瘤癌变的过程中可能受到抑制。联合检测VEGF、Endothelin-1和Endostatin的表达对筛选高危大肠腺瘤、判断大肠癌的发生发展、转移及预后具有重要的参考价值。

难治性胃溃疡患者血浆Endothelin-1浓度检测的意义

目的:检测难治性胃溃疡患者血浆Endothe lin-1水平,探讨其在难治性溃疡发病中的作用。方法:64例胃溃疡病患者给予正规抗溃疡病治疗,其中34例12周后经胃镜证实溃疡未愈合(难治性溃疡组);30例痊愈(溃疡愈合组)。分别检测两组患者治疗前后的血浆ET-1水平,20例健康体检者作为对照组。结果:治疗前,难治性溃疡组的平均血浆浓度(62.71±12.38)μg/L,显著低于溃疡愈合组(96.39±15.25)μg/L及健康对照组(86.29±11.23)μg/L),差异均有显著性(P<0.05),溃疡愈合组与对照组间差异无显著性。两组患者治疗前后的ET-1水平均无显著性变化。结论:难治性溃疡患者的ET-1水平偏低,可能导致新生血管的形成不足使得溃疡久治不愈。

The Expression of Endothelin Receptor B in Melanoma Cells A375 and Sk-mel-1 and the Proliferative Effects of Endothelin 3 on A375 Cells

In order to investigate the expression of endothelin receptor B （ETR-B） in human malignant melanoma （MM） cells A375 and SK-mel-1 and the proliferative effects of endothelin 3 （ET3） on A375 cells, RT-PCR was applied to detect the expression of ETR-B gene in human MM cells A375 and SK-mel-1. MTT method was used to evaluate the growth enhancing effects of ET3 on A375 cell line in vitro. The results showed that ETR-B gene was expressed in both MM A375 and SK-mel-1 cells. ET3 had stronger ability to enhance the proliferation of A375 cells in vitro in a concentration-dependent manner. It was suggested that ET3/ETR-B might play an important proliferative role in MM.

CLINICAL RESEARCH OF IMPACTS ON PLASMA ENDOTHELIN AND INTELLIGENCE IN MULTI-INFARCT DEMATIA TREATED WITH CLUSTER PRICKING ON HEAD POINTS

Objective To probe into the impacts on the therapeutic effects and endothelin （ET） in multi-infarct dementia （MID） treated with cluster pricking on head points.Methods 60 cases of MID were randomized into acupuncture group and western medicine group,treated with cluster pricking on head points and huperzien A tablet respectively.Plasma ET lever,HDS,ADL and CNFDS （clinical neurological functional defect scoring） were determined before treatment,and the statistical analysis showed that there were no significant difference （P〉0.05）.Results In 8-week treatment,ET level in both groups were decreased,but it was decreased much more obviously in acupuncture group,indicating significant difference in the statistical comparison （P〈0.05）.The scores of HDS and ADL were all up in acupuncture and western medicine groups,but the significant statistical difference was obtained in the comparison between acupuncture group and western medicine group （P〈0.05）.In acupuncture group,the result of CNFDS was much down comparing with that before the treatment,indicating significant difference （P〈0.05）;but in western medicine group,there was no significant difference in CNFDS before and after treatment （P〉0.05）,suggesting that acupuncture reduces CNFDS of MID patient,neither for western medicine.Conclusion Cluster pricking on head points improves the intelligence of MID patient,reduces ET level and grades up HDS and ADL,moreover,it reduces CNFDS of MID patients and releases the symptoms.

Correlation between Pulmonary Endothelin Receptors and Alveolar-arterial Oxygen Gradient in Rats with Hepatopulmonary Syndrome

The correlation between pulmonary endothelin receptors and alveolar-arterial oxygen gradient （A aDO2） in rats with hepatopulmonary syndrome was investigated. Animals were divided into 2 groups： Sham operated （Sham） group and common bile duct ligation （CBDL） group. Arterial blood gas was evaluated by a blood gas analyzer. The concentrations of ET-1 in blood and lung tissue sample were evaluated by radioimmunoassay. The distribution and expression of two kinds of subtype receptor of ET-1, ETRA and ETRB were examined by in situ hybridization. The results showed that the level of A aDO2, was higher in CBDI. group than that in Sham group （P〈0.05）. The levels of plasma and pulmonary ET-1 in CBDL group were both higher than in Sham group （P〈0.05 ）. There was no significant difference in average A of ETRA between two groups by imaging analysis （0.21±0.06 vs 0.22±0.08, P〉0.05）, while that of ETRB was higher in CBDI. group than in Sham group （0.58±0.16 vs 0.28±0.07, P〈0.05）. The expression of ETRBinlung was positively correlated with A aDO2（P〈0.05）. It was concluded that the widened A-aDO2 may be related with enhancement of the expression of ETRB in lung.

MUTATION OF THE ENDOTHELIN-B RECEPTOR AND THE ENDOTHELIN-3 GENE IN CHINESE SPORADIC CASES OF HIRSCHSPRUNG'S DISEASE

Objective To investigate the mutation of endothelin receptor B (EDNRB) gene and endothelin 3 (EDN 3) gene in sporadic Hirschsprungs disease (HD) in Chinese population. Methods Genomic DNA was extracted from bowel tissues of 34 unrelated HD patients which were removed by surgery. Exon 3, 4, 6 of EDNRB gene and Exon 1, 2 of EDN 3 gene were amplified by polymerase chain reaction (PCR) and analyzed by single strand conformation polymorphism (SSCP).Results EDNRB mutations were detected in 2 of the 13 short segment HDs. One mutant was in the exon 3; the other one was in the exon 6. EDN 3 mutation was detected in 1 of the 13 short segment HDs and in the exon 2. Both EDNRB mutation and EDN 3 mutation were detected in one short segment HD. No mutations were detected in the ordinary or long segment HD. Conclusion The mutations of EDNRB gene and EDN 3 gene are found in the short segment HD of sporadic Hirschsprung's disease in Chinese population, which suggests that the EDNRB gene and EDN 3 gene play important roles in the pathogenesis of HD. the mutations of EDNRB and EDN 3 lead to the maldevelopment of the enteric nervous system.

Studies of the antagonistic effect of BQ-123 on cerebral vasospasm induced by intracisternal injection of endothelin-1 and subarachnoid hemorrhage

To clarify whether the endothelin A (ETA)-receptor antagonist BQ-123 can prevent the development of cerebral vasospasm (CVS) induced by endothelin (ET-1) and subarachnoid hemorrhage (SAH), which has been controversia11y reported by various authors. We have performed investigations in anesthetized Sprague-Dawley rats- Intracisternal injection (i. c. ) of ET-l (10-11, 10-10, 10-9 mol/kg) could induce acute dose-dependent CVS, furthermore, the highest dose of ET-l (lO-’ mo1/kg) had a biphasic response in CVS of a 24-hour duration. However, the CVS by ET-1 (10-9 mol/kg) could be prevented effectively by previous i. c. of BQ-123 in a dose-dependent manner (10-9, 10-8, 10-7 mol/kg), of which the i. c- of BQ-123 (10-7mol/kg) could abolish the CVS completely. i. c. of BQ-123 (10-7 mol/kg) before SAH induced by a single i. c, of 150 pl autologous fresh blood directly to the Willis circle cou1d prevent the following CVS largely, which was a biphasic response and long-lasting (duration of 72 h). We conclude that subarachnoid application of ETA-receptor antagonist can effecti vely prevent CVS induced by ET-1 and SAH, and ET-1 may be the major mediator responsible for the CVS following SAH.

Plasma endothelin and nitric oxide levels in patients with acute pancreatitis

Objective: To explore the changes of plasma endothelin(ET) and nitric oxide (NO) levels in patients with a-cute pancreatitis.Methods: The level of plasma ET was measured by ra-dioactive-immunoassay, and NO by spectrophotometry.Results: The levels of ET, NO and the ET/NO ratioin patients with severe acute pancreatitis(SAP) within24 hours in hospital were all significantly higher thanthose in other groups of patients [(176±8)pg/ml,(97±11) μmol/L, and 1.83±0.12, P<0.01]. Com-pared to healthy controls(N), the levels of ET and NOin patients without pancreatitis acute abdomen (NAP)and patients with mild acute pancreatitis (MAP) in-creased significantly (P<0.01). After appropriate treat-ment, the levels of ET and NO in the MAP groupwere lower (P<0.01). Compared with those beforetreatment, the levels of ET and NO in the SAP groupon the 3rd and 7th day in hospital dropped signifi-cantly(P<0.01).The ET/NO ratio on the 7th daywas also lower than that on admission (P<0.01).Conclusions: The malfunction of endothelial cells andthe increased ET/NO ratio may be related to the mecha-nism of pancreatic microcirculatory disturbance in pa-tients with SAP; early dynamic determination of theseparameters may help predict the prognosis of SAP.

康柏西普联合PRP治疗缺血型CRVO引起新生血管性青光眼的效果及对房水Klotho和Endothelin-1的影响

目的探讨康柏西普联合全视网膜光凝(PRP)治疗缺血型视网膜中央静脉阻塞(CRVO)引起新生血管性青光眼(NVG)的效果及对房水Klotho和Endothelin-1的影响。方法选取2019年12月—2020年12月80例缺血型CRVO引起的NVG(80只眼),根据治疗方法不同分为对照组和研究组,每组40例(40只眼)。对照组采用PRP治疗,研究组采用康柏西普联合PRP治疗。对比两组综合疗效、不良事件及复发情况。比较两组治疗前后眼压和最佳矫正视力(BCVA),房水Klotho、Endothelin-1、血管内皮生长因子(VEGF)、血小板反应蛋白-1(TSP-1)、细胞色素C(CytC)、线粒体融合蛋白1(Mfn1)水平,以及视网膜中央动脉舒张末期血流速度(EDV)、收缩期峰值血流速度(PSA)。结果研究组总有效率高于对照组(P<0.05)。治疗前、治疗后4和8周,两组眼压及房水Endothelin-1、VEGF、TSP-1、CytC水平呈降低趋势,BCVA、房水Klotho和Mfn1水平、视网膜中央动脉EDV和PSA呈升高趋势;且研究组治疗后4、8周上述指标降低和升高程度均优于对照组(P<0.05)。研究组不良事件发生率低于对照组(P<0.05)。两组复发率比较差异无统计学意义(P>0.05)。结论采用康柏西普联合PRP治疗缺血型CRVO引起NVG,能显著提高治疗效果,进一步提高患者视力水平,抑制新生血管生成,改善房水Klotho、Endothelin-1水平。

Effects of endotoxin on endothelin receptor in hepatic and intestinal tissues after endotoxemia in rats

INTRODUCTIONEndothelins(ETs) has a potent and sustainedvasoconstrictive effect on a variety of blood vessels.The vascular smooth muscle cell (VSMC)is thetarget for ETs.VSMC of the whole body containsendothelin receptor (ETR).A great number ofexperiments have shown that three distinctcomplementary DNAs of ETR have been identifiedi.e.,endothelin A receptor(ET_A receptor),endothelin B receptor(ET_B receptor)

Increased endothelin receptor B and G protein coupled kinase-2 in the mesentery of portal hypertensive rats

AIM: To elucidate the mechanisms of mesenteric vasodilation in portal hypertension (PHT), with a focus on endothelin signaling. METHODS: PHT was induced in rats by common bile duct ligation (CBDL). Portal pressure (PP) was measured directly via catheters placed in the portal vein tract. The level of endothelin-1 (ET-1) in the mesenteric circulation was determined by radioimmunoassay, and the expression of the endothelin A receptor (ETAR) and endothelin B receptor (ETBR) was assessed by immunofluorescence and Western blot. Additionally, expression of G protein coupled kinase-2 (GRK2) and β-arrestin 2, which influence endothelin receptor sensitivity, were also studied by Western blot. RESULTS: PP of CBDL rats increased significantly (11.89 ± 1.38 mmHg vs 16.34 ± 1.63 mmHg). ET-1 expression decreased in the mesenteric circulation 2 and 4 wk after CBDL. ET-1 levels in the systemic circulation of CBDL rats were increased at 2 wk and decreased at 4 wk. There was no change in ETAR expression in response to CBDL; however, increased expression of ETBR in the endothelial cells of mesenteric arterioles and capillaries was observed. In sham-operated rats, ETBR was mainly expressed in the CD31+ endothelial cells of the arterioles. With development of PHT, in addition to the endothelial cells, ETBR expression was noticeably detectable in the SMA+ smooth muscle cells of arterioles and in the CD31+ capillaries. Following CBDL, increased expression of GRK2 was also found in mesenteric tissue, though there was no change in the level of β-arrestin 2. CONCLUSION: Decreased levels of ET-1 and increased ETBR expression in the mesenteric circulation following CBDL in rats may underlie mesenteric vasodilation in individuals with PHT. Mechanistically, increased GRK2 expression may lead to desensitization of ETAR, as well as other vasoconstrictors, promoting this vasodilatory effect.

Plasma endothelin in patients with endotoxemia and dynamic comparison between vasoconstrictor and vasodilator in cirrhotic patients

INTRODUCTIONPortal hypertension is a common clinical syndromecharacterized by an abnormal increase in portalblood to the systemic circulation, bypassing theliver. Recent studies have reported that humoralsubstances play an important role in thepathogenesis of portal hypertension, either byincreasing vascular resistance at both theintrahepatic and porto-collateral sites or affectingsplanchnic vasodilation with a concomitant increasein parto-collateral blood flow[1-6]

内皮素(Endothelin)对大鼠心血管功能的影响

给正常大鼠静脉注射3μg/Kg内皮素,可引起动脉血压下降和心肌收缩力减弱,使LVPSP和±LV dP/dtmax呈显著而持久的降低。给利血平和阿托品化的大鼠注射同样剂量的内皮素,使血压一过性升高。用不同剂量的内皮素灌流心脏,可引起冠状动脉收缩,使灌流压升高,并有强大的抑制心功能的作用,使LVPSP和±LV dp/dt max显著降低,且具有剂效关系。在浓度为10^(-8)M时,可出现心肌挛缩和心律失常,内皮素具有强大的收缩主动脉环的作用,其ED_(50)为3×10~8M,较NE强约5倍。提示内皮素可能是在机体严重损伤(如休克、缺血、缺氧)等条件下,血管内皮细胞产生、释放或漏出的一种致病因子,参与某些疾病的发病过程。

Associations of big endothelin-1 and C-reactive protein in atrial fibrillation

Background Atrial fibrillation （AF） is associated with inflammation and endothelial dysfunction. However, the association between inflammation （as indexed by high-sensitivity C-reactive protein, hs-CRP） and endothelial function [as indexed by big endothelin-1 （ET-1）] in AF patients remains unclear. Methods We enrolled 128 patients with lone AF, among which 83 had paroxysmal AF, and 45 had persistent AF. Eighty-two age- and gender-matched controls of paroxysmal supraventricular tachycardia without AF history were evaluated. Plasma hs-CRP, big ET-1 levels and other clinical characteristics were compared among the groups. Results Patients with persistent AF had higher hs-CRP concentrations than those with paroxysmal AF （P 〈 0.05）, both groups had higher hs-CRP level than controls （P 〈 0.05）. Patients with persistent AF had higher big ET-1 level than those with paroxysmal AF, although the difference did not reach the statistical significance （P 〉 0.05）, and both groups had higher big ET-1 levels than controls （P 〈 0.05）. Multiple regression analyses revealed hs-CRP as an inde- pendent determinant of AF （P 〈 0.001）. Further adjusted for big ET-1, both big ET-1 and hs-CRP were independent predictors for AF （P 〈 0.001）, but the odds ratio for hs-CRP in predicting AF attenuated from 8.043 to 3.241. There was a positive relation between hs-CRP level and big ET-1 level in paroxysmal AF patients （r = 0.563, P 〈 0.05）, however, the relationship in persistent AF patients was poor （r = 0.094, P 〈 0.05）. Conclusions Both plasma hs-CRP and big ET-1 levels are elevated in lone AF patients, and are associated with AF. In paroxysmal lone AF patients, there were significant positive correlations between plasma hs-CRP level and big ET- 1 level.

Melatonin abates liver ischemia/reperfusion injury by improving the balance between nitric oxide and endothelin

BACKGROUND: Melatonin exerts complex physiological and pharmacological effects on multiple systems and organs. We hypothesized that melatonin might abate ischemia/ reperfusion (I/R) injury in the liver by inhibiting excessive oxidative stress and keeping nitric oxide (NO) from being scavenged by free radicals. The aim of the present study was to investigate whether melatonin protects the liver from I/R injury and, if so, by what underlying mechanism. METHODS: Under anesthesia, Wistar rats were intraperi- toneally injected with 20 mg/kg melatonin (dissolved in physiological saline containing 4% ethanol, Mel group), 4% alcohol (Alc group), or physiological saline (NS group). The artery, portal vein and bile duct of the left lobe of the liver were clamped for 60 minutes and then released. At different time points after I/R, the rats were sacrificed and blood samples were collected to measure the levels of serum alanine aminotransferase (ALT), lactic dehydrogenase (LDH), and NO. Hepatic tissue samples were collected for measuring endothelin expression by immunohistochemical staining and for routine morphological and histological examination. RESULTS: The levels of both ALT and LDH in the Mel group were significantly reduced for up to 24 hours after I/R compared with the Alc and NS groups (P<0.05). The levels of NO in the Mel group were significantly elevated for up to 12 hours after I/R relative to the NS group (P<0.05). The NO levels were also elevated at 0.5 and 6 hours after I/R in the Alc group (P<0.05). The immunohistochemical staining of hepatic tissue showedthat endothelin-positive cells were significantly fewer in the Mel group than in the Alc and NS groups at 6 hours after I/R (P<0.01). The necrosis of hepatocytes and the destruction of hepatic cords in the Alc and NS groups were greatly improved in Mel-treated rats, which is in concert with our functional data. CONCLUSIONS: Pretreatment with melatonin increased NO bioavailability and decreased endothelin expression, and consequently played a protective role in preserving both liver function and structure during ischemia and reperfusion injury.