Increase in nitric oxide bioavailability improves endothelial function in endothelin-1 transgenic mice.

BACKGROUND: Endothelin-1 (ET-1) has been described as a very potent vasoconstrictor. Nevertheless, transgenic mice overexpressing ET-1 have been shown to exhibit normal blood pressure. We thus hypothesized that vascular ET-1 effects may be antagonized by increased activity of other regulatory systems, such as the increase in bioavailability of the endothelial counterpart of ET-1, nitric oxide (NO). METHODS: Endothelium-dependent and -independent vascular function was assessed as relaxation/contraction of isolated preconstricted aortic rings to acetylcholine (10(-10)-10(-4) mol/l), sodium nitroprusside (10(-10)-10(-4) mol/l), ET-1 (10(-10)-10(-7) mol/l) and big ET-1 (10(-10)-10(-7) mol/l), respectively, in ET-1 transgenic mice and corresponding controls. To unmask the impact of the NO system, we furthermore analysed vessel rings incubated in vitro with the NO-synthase inhibitor L-N(G)-nitroarginine methyl ester (L-NAME, 10(-4) mol/l). RESULTS: Maximum endothelium-dependent relaxation was enhanced in ET-1 transgenic mice (93+/-3% vs 84+/-4% for wild-type littermates; P<0.05) and was inhibited by preincubation with L-NAME in both ET-transgenic mice and wild-type littermates (11+/-5% vs 9+/-4% maximum relaxation, respectively). Endothelium-independent relaxation was similar among all groups. Maximum vascular contraction to ET-1 and big ET-1 was reduced in ET-1 transgenic mice (P<0.05 vs wild-type littermates). Preincubation with L-NAME reduced this difference, indicating the involvement of augmented NO availability. Correspondingly, urinary nitrate/nitrite excretion was significantly elevated in ET-1 transgenic mice. CONCLUSIONS: These data suggest that in transgenic mice overexpressing ET-1, increased NO bioavailability counteracts the contractile potency of elevated ET-1 levels and leads to an improvement of endothelium-dependent relaxation. Thus, in the presence of an activated ET system, up-regulation of NO production may be capable of maintaining vascular tone in a normal range and therefore may prevent the development of hypertension.     

Vasopeptidase inhibition restores renovascular endothelial dysfunction in salt-induced hypertension.

Renovascular hemodynamics plays a pivotal role in the regulation of BP. The effect of the vasopeptidase inhibitor omapatrilat (O) and the ACE-inhibitor captopril (C) on endothelial function in the renal circulation in salt-induced hypertension were investigated. Dahl salt-sensitive rats (n = 6 per group) on standard or salt-enriched chow were treated for 8 wk with O (36 +/- 4 mg/kg per d), C (94 +/- 2 mg/kg per d), or placebo. Renal arteries were suspended in organ chambers for isometric tension recording. Vascular hypertrophy was assessed by determination of standardized heart weight and aortic weight, and morphologic analysis of glomerular injury was performed. Systolic BP of salt-fed, placebo-treated animals increased to 196 +/- 6 mmHg, which was reduced by O (162 +/- 5 mmHg; P < 0.05) and C (164 +/- 7 mmHg; P < 0.05) to a comparable degree. In salt-induced hypertension, endothelium-dependent relaxations in renal arteries (56 +/- 6 versus 100 +/- 6%; P < 0.05) as well as contractions to endothelin-1 (ET-1) (98 +/- 5% versus 128 +/- 5%; P < 0.05) and big ET-1 (47 +/- 6% versus 116 +/- 7%; P < 0.05) were markedly reduced as compared with control animals, whereas standardized aortic weight and heart weight (4.9 +/- 0.4 versus 3.2 +/- 0.3 g/kg; P < 0.05) increased. Treatment with O restored endothelium-dependent relaxations (88 +/- 6%; P < 0.05 versus C) and contractions to ET-1 (120 +/- 6%) and big ET-1 (98 +/- 9%). O prevented vascular hypertrophy (0.23 +/- 0.019 mg/mm(2) versus 0.31 +/- 0.018 mg/mm(2) in high-salt diet; P < 0.05), but, in contrast to C, it only had a modest effect on glomerular injury. In conclusion, O restored renovascular endothelial function and prevented vascular hypertrophy in salt-induced hypertension and therefore may advance as a beneficial approach in the therapy of various forms of hypertension.     

Influence of aldosterone vs. endothelin receptor antagonism on renovascular function in liquorice-induced hypertension.

BACKGROUND: The enzyme 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) provides mineralocorticoid receptor specificity for aldosterone by metabolizing glucocorticoids to their receptor inactive 11-dehydro derivatives. Inhibition of 11beta-HSD2 by liquorice-derived glycyrrhizic acid (GA) therefore results in sodium retention and hypertension. The present study investigated the effect of the aldosterone receptor antagonist spironolactone in comparison with the endothelin ET(A) receptor antagonist darusentan on renovascular endothelial function in liquorice-induced hypertension. METHODS: GA, a recognized inhibitor of 11beta-HSD2 was supplemented to the drinking water (3 g/l) of Wistar Kyoto rats over a period of 21 days. From day 8 to 21, spironolactone (5.8+/-0.6 mg/kg/day), darusentan (45.2+/-6.5 mg/kg/day), or placebo was added to chow (n=7 per group). After the animals were killed, vascular function of isolated renal artery segments was assessed by isometric tension recording. RESULTS: Relaxation of pre-constricted renal artery segments in response to acetylcholine (10(-10) to 10(-5) mol/l) was impaired by GA as compared with controls (12+/-4% vs 98+/-5% of norepinephrine 3x10(-7) mol/l), whereas endothelium independent relaxations were unaffected. Endothelin receptor antagonism improved renovascular endothelium-dependent relaxation (32+/-4%, P<0.05 vs placebo) whereas endothelium-dependent relaxation was completely normalized by aldosterone receptor antagonism (85+/-4%, P<0.01 vs placebo). CONCLUSIONS: In GA-induced hypertension, both aldosterone receptor antagonism and endothelin receptor antagonism normalize blood pressure and improve renovascular function and, thus, may represent a new therapeutic approach in cardiovascular disease associated with impaired 11beta-HSD2 activity.     

Genetic analysis of nitric oxide and endothelin in end-stage renal disease.

BACKGROUND: Genetic factors have been implicated in the development of the common aetiologies of end-stage renal disease (ESRD), including renal failure attributed to hypertension, diabetes mellitus, systemic lupus erythematosus and human immunodeficiency virus infection. Nitric oxide (NO) and endothelin are powerful vasoactive mediators involved in inflammation and regulation of vascular tone and blood pressure. We evaluated the role of the neuronal constitutive (NOS1) and endothelial constitutive (NOS3) nitric oxide synthase genes and the endothelin-1 (EDN-1) gene in predisposition to chronic renal failure in African-Americans. METHODS: The study population for the linkage and association analyses in ESRD consisted of 361 individuals from 168 multiplex African-American families. These individuals comprised 207 unweighted sibling pairs concordant for all-cause ESRD. Microsatellite markers NOS1B (NOS1), D7S636 (NOS3) and CPHD1-1/2 (EDN-1) were genotyped in the sample. In addition, a mutation, Glu298Asp, in exon 7 of NOS3 and a 27 bp variable number tandem repeat (VNTR) marker in intron 4 of NOS3 were evaluated in the sibling pairs and in an additional 92 unrelated African-Americans with type 2 diabetes mellitus-associated ESRD (singletons). Association analyses utilized the relative predispositional effect method. Model independent linkage analyses were performed using GeneHunter-plus and MapMaker/SIBS (exclusion analysis) software. RESULTS: Significant evidence for association with ESRD was detected for alleles 7 and 9 of the NOS1 gene (11.9 and 34.2%, respectively, in unrelated probands of ESRD families versus 6.5 and 27.5%, respectively, in race-matched controls, both P:<0.01). These associations were maintained when the unrelated first sibling from each family was used in a case-control comparison and was most pronounced in the non-diabetic ESRD cases. The NOS3 and EDN-1 markers failed to provide consistent evidence for association in the sibling pairs and the diabetic ESRD singletons, although we identified two novel endothelial constitutive NOS4 (ecNOS4) VNTR alleles in African-Americans. Significant evidence for linkage was not detected between the NOS genes or the EDN-1 gene in either all-cause ESRD or when the ESRD sibling pairs were stratified by aetiology (type 2 diabetic ESRD or non-diabetic aetiologies). CONCLUSION: Based upon the consistent allelic associations, we believe that further evaluation of the NOS1 gene in ESRD susceptibility in African-Americans is warranted.     

Vasopeptidase inhibition normalizes blood pressure and restores endothelial function in renovascular hypertension

BACKGROUND/AIMS: Vasopeptidase inhibitors by definition inhibit both angiotensin-converting enzyme (ACE) and neutral endopeptidase (NEP), therefore they may exceed the effect of ACE inhibitors in the treatment of hypertension. The present study investigated the effect of the vasopeptidase inhibitor AVE7688 in comparison to the ACE inhibitor ramipril on systolic blood pressure (SBP) and endothelial function in renovascular hypertension. METHODS: Wistar-Kyoto rats with renovascular hypertension (two-kidney one-clamp-model) were randomized 2 weeks after unilateral clamping of the right renal artery for 3 weeks' oral treatment with either AVE7688 (30 mg/kg/day), ramipril (1 mg/kg/day) or placebo. SBP was measured by the tail-cuff method and endothelium-dependent and -independent vascular function was assessed in isolated preconstricted (norepinephrine 10(-7) mol/l) aortic rings as relaxation to acetylcholine (10(-10)-10(-4) mol/l) and sodium nitroprusside (10(-10)-10(-4) mol/l), respectively. RESULTS: Two weeks after clamping, SBP was significantly elevated (196 +/- 16 vs. 145 +/- 8 mm Hg for sham-operated rats; p < 0.01) and further increased in placebo-treated animals to 208 +/- 19 mm Hg. Treatment with AVE7688 and ramipril had a similar blood pressure-lowering effect (119 +/- 8 and 124 +/- 10 mm Hg, respectively; p < 0.01 vs. placebo). Maximum endothelium-dependent relaxation was reduced in hypertensive rats (72 +/- 6 vs. 99 +/- 7% in control rats; p < 0.05). Endothelium-dependent relaxation was restored by AVE7688 (101 +/- 6%) and ramipril (94 +/- 8%), respectively, whereas endothelium-independent relaxation was comparable in all groups. CONCLUSION: In renovascular hypertension the vasopeptidase inhibitor AVE7688 exhibited similar blood pressure-lowering and endothelial protective properties as compared to the ACE inhibitor ramipril. Therefore, in high renin models of hypertension, vasopeptidase inhibition may be considered an alternative treatment option to ACE inhibition.     

Oxygen species in the microvascular environment: regulation of vascular tone and the development of hypertension.

Derangements of the three endothelium-related vasodilator systems (prostaglandins, endothelium-derived hyperpolarizing factor(s) and nitric oxide) cause the endothelial dysfunction observed in hypertension. Free radical-induced nitric oxide degradation plays a crucial role in hypertension. An increase in superoxide producing enzymes such as NAD(P)H oxidase and xanthine oxidase has been demonstrated. Superoxide dismutase may correct endothelial dysfunction in vitro and superoxide dismutase mimetics can lower blood pressure in experimental animals. Antioxidant agents and xanthine oxidase-inhibiting compounds have been used in humans. In addition, the synthesis of vasoconstrictor peroxides derived from the activity of cyclooxygenase in the endothelium and the vascular smooth muscle is stimulated by the OH. radical. Hydrogen peroxide levels are augmented in hypertension, but its role is unclear because recent investigations have shown that this substance may act as a hyperpolarizing factor. It is thought that the therapeutic benefit of anti-hypertensive drugs, such as calcium antagonists and angiotensin-converting enzyme inhibitors, could be in part due to an inhibition of free radical production. A role of superoxide in the endothelial dysfunction and hypertension of chronic renal failure has also been suggested by recent animal experiments.     

The pathogenesis of pulmonary hypertension in haemodialysis patients via arterio-venous access.

BACKGROUND: We recently have shown a high incidence of unexplained pulmonary hypertension (PHT) in end-stage renal disease (ESRD) patients on chronic haemodialysis (HD) therapy via arterio-venous (A-V) access. This study evaluated the possibility that PHT in these patients is triggered or aggravated by chronic HD via surgical A-V access, and the role of endothelin-1 (ET-1) and nitric oxide (NO) in this syndrome. METHODS: Forty-two HD patients underwent clinical evaluation. Pulmonary artery pressure (PAP) was evaluated using Doppler echocardiography. Levels of ET-1 and NO metabolites in plasma were determined before and after the HD procedure and were compared between subgroups of patients with and without PHT. RESULTS: Out of 42 HD patients studied, 20 patients (48%) had PHT (PAP = 46+/-2; range 36-82 mmHg) while the rest had a normal PAP (29+/-1 mmHg) (P<0.0001). HD patients with PHT had higher cardiac output compared with those with normal PAP (6.0+/-1.2 vs 5.2+/-0.9 l/min, P<0.034). HD patients, with or without PHT, had elevated plasma ET-1 levels compared with controls (1.6+/-0.7 and 2.4+/-0.8 fmol/ml vs 1.0+/-0.2, P<0.05) that remained unchanged after the HD procedure. HD patients without PHT and control subjects showed similar basal plasma levels of NO2 + NO3 (24.2+/-5.2 vs 19.7+/-3.1 microM, P>0.05) that was significantly higher compared with HD patients with PHT (14.3+/-2.3 microM, P<0.05). HD therapy caused a significant increase in plasma NO metabolites that was greater in patients without PHT (from 24.2+/-5.2 to 77.1+/-9.6 microM, P<0.0001, and from 14.3+/-2.3 to 39.9+/-11.4 microM, P<0.0074, respectively). Significant declines in PAP (from 49.8+/-2.8 to 38.6+/-2.2 mmHg, P<0.004) and cardiac output (CO) (from 7.6+/-0.6 to 6.1+/-0.3 l/min, P<0.03) were found in 11 HD patients with PHT that underwent successful transplantation. Similarly, temporary closure of the A-V access by a sphygmomanometer in eight patients with PHT resulted in a transient decrease in CO (from 6.4+/-0.6 to 5.3+/- 0.5 l/min, P = 0.18) and systolic PAP (from 47.2+/-3.8 to 34.6+/-2.8 mmHg, P<0.028). CONCLUSIONS: This study demonstrates a high prevalence of PHT among patients with ESRD on chronic HD via a surgical A-V fistula. In view of the vasodilatory and antimitogenic properties of NO, it is possible that the attenuated basal and HD-induced NO production in patients with PHT contributes to the increased pulmonary vascular tone. Furthermore, the partial restoration of normal PAP and CO in HD patients that underwent either temporal A-V shunt closure or successful transplantation indicates that excessive pulmonary blood flow is involved in the pathogenesis of the disease.     

肝硬化门脉高压鼠血浆内皮素变化

目的研究门脉高压时血浆内皮素（ＥＴ）变化的可能机制。方法测定ＳＤ、ＩＨＰＨ、ＰＣＳ组大鼠平均动脉压（ＭＡＰ）、门静脉压（ＦＰＰ）以及腹主动脉、门静脉、肝静脉血中内皮素（ＥＴ）和一氧化氮（ＮＤ）含量。结果与ＳＯ鼠相比，ＰＣＳ鼠和ＩＨＰＨ鼠血浆内皮素水平明显下降（Ｐ＜０．０５），但ＰＣＳ鼠与ＩＨＰＨ鼠间的差异无显著性意义。血浆ＥＴ水平与ＮＯ水平呈显著负相关（ｒ＝－０．５７２３，ｎ＝２９，Ｐ＜０．０１）。结论肝硬化门静脉高压大鼠血中ＥＴ浓度下降主要是肝内血管内皮细胞和肝窦内皮细胞减少，使ＥＴ合成减少所致。此外，ＮＯ升高可能抑制ＥＴ产生，这也是导致ＥＴ减少的原因。【关键词】##4大鼠;;肝硬化;;门静脉高压症;;内皮素;;一氧化氮     

Vascular effects of poly-N-acetylglucosamine in isolated rat aortic rings.

BAACKGROUND: Poly-N-acetylglucosamine (p-GlcNAc) is a secretion of marine diatoms that is known to be useful in controlling bleeding. As a component of promoting hemostasis, p-GlcNAc is thought to exert vasoconstrictor effects in arteries. The present study was undertaken to determine whether p-GlcNAc induced a significant vasoconstrictor effect and, if so, what the mechanism of this effect might be. MATERIALS AND METHODS: We examined vascular effects of p-GlcNAc on isolated aortic rings obtained from Sprague-Dawley rats. The rings were suspended in organ baths and precontracted with U46619, a thromboxane A2 mimetic. RESULTS: p-GlcNAc produced a concentration-dependent vasoconstriction over the range of 14 to 100 microg/ml. At a concentration of 100 microg/ml, p-GlcNAc significantly contracted aortic rings by 133 +/- 20 mg of developed force (P < 0.01). Neither a deacetylated derivative of p-GlcNAc nor a structurally related macromolecule, chitin, contracted rat aortic rings, indicating a specificity for p-GlcNAc. The vasoconstriction to p-GlcNAc was totally abolished in deendothelialized rat aortic rings, suggesting that an endothelial component is essential to the vasoconstriction. Pretreatment with the endothelin ET(A) receptor antagonist, JKC-301 (0.5 and 1 microM), significantly diminished p-GlcNAc-induced vasoconstriction by 57 to 61% (P < 0.01). However, p-GlcNAc did not significantly diminish nitric oxide release from rat aortic endothelium. CONCLUSION: These results provide evidence that p-GlcNAc significantly contracts isolated rat aortic rings via an endothelium-dependent mechanism, partly via enhancement of endothelin-1 release from endothelial cells.     

周围动脉硬化闭塞症血管内皮细胞损伤的观察

目的：探讨血管内皮细胞损伤和肿瘤坏死因子在周围动脉硬化闭塞症发病中的临床意义。方法：对５０例老年闭塞性动脉硬化患者进行血浆内皮素、一氧化氮、肿瘤坏死因子及外周循环内皮细胞检查，检测方法分别为放射免疫测定、亚硝酸盐比色法和Ｔａｋａｈａｓｈｉ法。结果：５０例患者均呈高内皮素、高肿瘤坏死因子、低一氧化氮血症以及外周循环内皮细胞数目明显增加（Ｐ＜０．０１）现象，且同疾病严重程度密切相关。结论：本研究结果提示血管内皮细胞损伤及肿瘤坏死因子参与了周围动脉硬化闭塞症的形成和发展     

硬膜外阻滞对妊娠高血压综合征患者血浆一氧化氮和内皮素含量的影响

目的 研究硬膜外阻滞前后妊高征患者血浆中一氧化氮（NO）和内皮素（ET）的变化。方法 选择20例择期剖宫产患者,正常妊娠组（NLP组）10例,妊高征组（PIH组）中度妊高征患者10例,分别于硬膜外阻滞前及阻滞完善后抽取母体静脉血,测定血浆一氧化氮和内皮素的浓度。结果 阻滞前PIH组血浆NO浓度明显低于NLP组（P＜0．01）,ET含量显著高于NLP组（P＜0．01）;阻滞后两组血浆NO水平均显著升高（P＜0．05）,ET水平明显降低（P＜0．05）。结论 血浆中NO含量降低和ET浓度增高是妊高征发病的一个重要环节,硬膜外阻滞可使妊高征患者血浆NO水平和ET浓度降低,是一种有效和安全的麻醉方法。     

The roles of free oxygen radicals, nitric oxide, and endothelin in caustic injury of rat esophagus

Purpose

The authors aimed to find out the roles of free oxygen radicals, nitric oxide (NO), and endothelin (ET) in caustic injury of rat esophagus.

Methods

Forty-five Wistar albino rats were used to form 6 groups. The study groups are summarized as 1, sham (S; n = 7); 2, sham + l-arginine (SA; n = 7); 3, sham + l-NAME (SN; n = 7); 4, injury (I; n = 8); 5, injury + l-arginine (IA; n = 8); 6, injury + l-NAME (IN; n = 8). Normal saline in the sham groups and 50% NaOH in the caustic injury groups were administered to the distal esophagus. Free oxygen radicals and NO were detected by chemiluminescence from tissue samples, and they were correlated with histologic examinations. Tissue ET was measured also with immunohistochemistry.

Results

The injury was verified histologically. Free oxygen radical levels were found to be increased as well as NO and ET with the caustic injury (P < .05). l-arginine caused a histologic increase in the injury that was close to statistical significance (P = .08). l-NAME showed no significant effect.

Conclusions

Free radicals, NO, and ET increase in the early phase of caustic esophageal injury. Understanding their early interactions during the caustic injury may help in future therapeutic strategies.     

Neurohormonal factors in the pathogenesis of essential hypertension

Summary: The level of arterial pressure in an individual is dictated by many interacting factors including neurohormonal systems. Heightened activity of pressor systems could contribute to the pathogenesis of essential hypertension; evidence for this is strongest for sympathetic overactivity in some young patients. Inadequacy of vasodilator systems, especially natriuretic peptides or nitric oxide, has also been suggested as central to the pathogenesis of essential hypertension although evidence is far from definitive. the existence of authentic ouabain in human plasma, let alone its pathophysiological importance in hypertension, is now in doubt. Information is awaited regarding the role of the endothelins and adrenomedullin in physiology and in essential hypertension.     

妊高征患者剖宫产术后硬膜外自控镇痛对一氧化氮和内皮素的影响

目的 探讨硬膜外自控镇痛(PCEA)对妊高征患者剖宫产术后血清一氧化氮(NO)和血浆内皮素(ET)的影响。方法 20例中、重度妊高征患者随机分成两组,Ⅰ组术后采用PCEA,Ⅱ组术后肌注哌替啶。于术前、术毕、术后24 h和48 h记录收缩压(SBP)、舒张压(DBP)和心率(HR),并抽取肘静脉血测NO和ET。结果 两组患者术毕、术后24 h和48 h的SBP和DBP均较术前明显降低(P<0.05,P<0.01),术后24 h和48 h Ⅰ组较Ⅱ组降低明显(P<0.05),各时期HR无明显变化(P>0.05);两组患者术毕、术后24 h和48 h ET较术前明显降低(P<0.05),Ⅰ组术后24 h和48h较Ⅱ组降低明显(P<0.05);两组术毕NO较术前明显降低(P<0.05),术后24 h和48 h又恢复到术前水平,两组间无显著性差异(P>0.05)。结论 PCEA能降低妊高征患者剖宫产术后ET水平,并使血压降低,对NO无明显影响。     

一氧化氮合酶、内皮素在门脉高压大鼠肠粘膜中的表达变化

目的　探讨一氧化氮合酶和内皮素 -1在门脉高压大鼠肠粘膜中的表达情况。方法　2 0只雄性SD大鼠随机分为实验组与对照组 ,实验组行门静脉两步结扎加左肾上腺静脉结扎 ;应用免疫组化SP染色法检测iNOS、ecNOS及ET -1在大鼠小肠和结肠粘膜中的表达情况。结果　门静脉完全结扎后两周 ,实验组大鼠门静脉压力较对照组明显增高 ;iNOS、ecNOS及ET -1在小肠粘膜中表达强度较对照组增强 ,iNOS及ET -1在结肠粘膜中表达较对照组增强。结论　门脉高压大鼠小肠、结肠粘膜局部病变中iNOS、ecNOS及ET -1的表达不完全一致     

Impaired endothelium-dependent vasodilatation in uraemia.

BACKGROUND: Patients with chronic renal failure (CRF) have a substantially increased risk of cardiovascular death, the proposed mechanisms being arrhythmias (left ventricular hypertrophy) and accelerated atherosclerosis. The vascular endothelium protects against the development of atherosclerosis principally by releasing vasoactive substances such as nitric oxide (NO) and endothelium-derived hyperpolarizing factor. In CRF there is accumulation of endogenous inhibitors of NO synthesis. In this present study we assessed endothelium-dependent vasodilatation in patients with advanced uraemia. METHODS: Sixteen uraemic patients (pre-dialysis and continuous ambulatory peritoneal dialysis) and 18 controls were studied. Forearm plethysmography was used to measure forearm blood flow and the changes induced by carbachol (endothelium-dependent vasodilator) and sodium nitroprusside (SNP; endothelium-independent vasodilator). The order of drugs infused was randomized between subjects. Dose response curves were constructed for each agent and area under the curve (AUC) calculated (arbitrary units). RESULTS: Overall, vasodilatation to SNP and carbachol was similar between uraemic patients and controls. However, it became apparent that there was a marked order effect for the drugs infused, such that infusion of SNP as the first agent blunted the subsequent response to carbachol. When only those patients and controls who received carbachol followed by SNP were studied (10 in each group), the response to carbachol in uraemic patients was attenuated compared to controls: AUC (median(range)) for uraemic patients 529.0 (150.9-834.7) compared to AUC for controls 703.9 (583.5-1576.6); P=0. 028. Vasodilatation to SNP was, however, similar between groups: AUC for uraemic patients 1475.0 (857.8-4717.1) compared to AUC for controls 1328.1 (216.6-3311.4); P=0.545. CONCLUSIONS: This study has demonstrated a marked drug order effect not previously described for forearm plethysmography. When the order effect was taken into account, this study demonstrated reduced vasodilatation to carbachol in uraemic patients with a preserved response to SNP. This pattern indicates impaired endothelium-dependent vasodilatation in uraemic patients, a defect that may predispose this group to accelerated atherosclerosis.     

胆石病员一氧化氮和内皮素的变化及其意义

探讨胆囊结石,胆石伴梗阻性黄疸时ＥＴ－１、ＮＯ变化及其临床意义。方法：前瞻性比较观测正常人、胆囊结石、胆石并黄疸病员血液ＮＯ、ＥＴ－１及肝功能指标。结果胆石并黄疸组：ＮＯ、白蛋白、球蛋白、ＡＬＴ、血清胆红素和另两组比较,有显著判别与ＥＴ－１、ＡＬＴ呈负相关。     

Reversal of renal lesions following interruption of nitric oxide synthesis inhibition in transgenic mice.

BACKGROUND: Renal fibrosis, a common complication of hypertension and diabetes is considered as a non-curable disease and is characterized by the abnormal accumulation of collagen I within the kidney. Chronic inhibition of nitric oxide (NO) synthesis is a model of hypertension associated with the development of nephroangiosclerosis. The present study investigated whether halt of NO inhibition leads to the regression of renal sclerotic lesions. METHODS: The NO deficiency (N(G)-nitro-L-arginine methylester; L-NAME) model of hypertension was applied in transgenic mice harbouring the luciferase reporter gene under the control of the collagen I-alpha2 chain promoter. RESULTS: Systolic pressure gradually increased following the administration of L-NAME, and reached 160 mmHg after 8-10 weeks. Activation of collagen I gene within the renal vasculature preceded the blood pressure increase and was accompanied by the appearance of sclerotic glomeruli and tubulointerstitial infiltration. After renal lesions had been established (20 weeks), animals were divided in three subgroups for an additional experimental period of 10 weeks: first group continued to receive L-NAME, in the second, L-NAME administration was stopped to allow endogenous NO synthesis and in the third the removal of L-NAME was combined with endothelin receptor antagonism. Removal of L-NAME decreased, without normalizing, systolic pressure and collagen I gene activity; renal morphology was substantially improved, and tubulointerstitial infiltration disappeared. Combination of L-NAME removal with endothelin antagonism normalized collagen I gene expression and further improved renal morphology without further decreasing blood pressure. CONCLUSION: Manipulating the balance between NO/vasoconstrictors in favour of NO could provide a curative approach against renal inflammatory and fibrotic complications associated to hypertension.     

Endothelin-1 and Nitric Oxide in Patients on Chronic Hemodialysis

Aim. To establish the role of endothelin-1 and nitric oxide in the pathogenesis of hypertension in patients on chronic aemodyalisis by correlating endothelin-1 and NO plasma concentrations to the level of arterial hypertension with respect to angiotensin-converting enzyme (ACE) inhibitor therapy. Methods. We determined plasma concentrations of endothelin-1 and NO in patients on chronic hemodialysis (CHD) before and after hemodialysis treatment. The study included 30 CHD patients and 20 healthy participants as controls. Correlation to blood pressure was determined, as well as the effect of ACE inhibitors on the relationship between both endothelin-1 and NO in correlation with arterial hypertension. Main findings.Endothelin-1 plasma concentration was significantly higher in CHD patients before hemodialysis treatment than in healthy controls. Endothelin-1 plasma concentration was also significantly higher in CHD patients after hemodialysis than in healthy controls. There was a significant decrease in endothelin-1 plasma concentration after hemodialysis in comparison with its values before hemodialysis. In CHD patients, a positive correlation was found between endothelin-1 plasma concentration and systolic blood pressure after hemodialysis, irrespective of ACE inhibitors therapy. In CHD patients taking ACE inhibitors, systolic blood pressure increased with increasing endothelin-1 plasma concentration before as well as after hemodialysis. In patients taking ACE inhibitors, there was a tendency for diastolic blood pressure to increase with an increase in endothelin-1 plasma concentration after hemodialysis and to decrease with an increase in NO plasma concentration. Conclusion. NO and endothelin-1 play a significant role in etiology of the hemodynamic changes of blood pressure during the dialysis.     

Endothelial nitric oxide synthase polymorphisms are associated with hypertension and cardiovascular disease in renal transplantation

Aim: Nitric oxide (NO), produced by the polymorphic endothelial nitric oxide synthase (NOS3), plays an important role in endothelial function. The aim was to determine the effect of NOS3 polymorphisms on hypertension and cardiovascular disease (CVD) in renal allograft recipients. Methods: Three polymorphisms of NOS3 were examined in 168 renal allograft recipients. A 27 base pair repeat sequence in intron 4 (NOS3 a/b), a single G→T substitution in exon 7 at nucleotide 894 and a T‐786C substitution in the promoter region were studied. Results: Significant differences in the frequencies of the 894T and ?786C alleles between allograft recipients and controls (n = 141) were demonstrated (894T: 40.5% vs 30.1%, P < 0.01; ?786C: 45.2% vs 34.4%, P < 0.01). There was a significant excess of both the 894T and ?786C alleles in hypertensive allograft recipients compared with normotensive allograft recipients and controls (894T: 41.7%, 35.7% and 30.1%, respectively, P < 0.025; ?786C: 47.4%, 37.1% and 34.4%, respectively, P < 0.01), and in allograft recipients with CVD compared with those without CVD and controls (894T: 47.2%, 38.6% and 30.1%, respectively, P < 0.025; ?786C: 54.2%, 42.8% and 34.4%, respectively, P < 0.01). Conclusion: The 894T and ?786C alleles of the NOS3 gene were significantly associated with both hypertension and CVD in renal allograft recipients.