Role of Na(+)-K(+)-ATPase in sodium nitroprusside-induced relaxation of pulmonary artery under hypoxia

BACKGROUND: The sodium pump (Na(+)-K(+)-ATPase) plays a part in the regulation of smooth muscle contractility, and alterations of enzyme activity by hypoxia could contribute to the mechanism of hypoxic pulmonary vasoconstriction. OBJECTIVE: To determine the role of Na(+)-K(+)-ATPase in the sodium nitroprusside (SNP)-induced relaxation of pulmonary artery in hypoxia. METHODS: Using isolated canine pulmonary arterial rings, we measured the relaxant responses of KCI-contracted tissues to SNP under hyperoxic (95% O2, 5% O2) and hypoxic conditions (5% O2, 5% CO2, 90% N2 in vitro. Na(+)-K(+)-ATPase activity was assessed by measuring ouabain-sensitive (86)Rb uptake. RESULTS: The SNP-induced relaxation was reduced under hypoxia, so that the maximal relaxation decreased from 80.1 +/- 8.6 to 57.8 +/- 6.8% (p < 0.01) and the concentration of SNP required to produce 50% relaxation increased from 1.9 +/- 0.4 x 10(-6) to 2.6 +/- 0.6 x 10(-5) M (p < 0.01). Addition of ouabain, an Na(+)-K(+)-ATPase inhibitor, attenuated the relaxant response to SNP and this inhibition was still observed under hypoxia. Incubation of endothelium-denuded rings with SNP caused dose-dependent increases in intracellular cGMP levels and ouabain-sensitive (86)Rb uptake, and these effects were not significantly altered by hypoxia. CONCLUSION: These results suggest that sarcolemmal Na(+)-K(+)-ATPase activity may be implicated in the mechanism of nitrovasodilator-induced vasodilation of pulmonary artery and may still be functioning under hypoxia.     

Cation fluxes and Na+-K+-activated ATPase activity in erythrocytes of patients with essential hypertension

Recently it has been claimed that the active potassium influx in erythrocytes of patients with essential hypertension would be increased. In view of the diagnostic and possibly therapeutic potential of this claim, we have determined the Na+-K+ activated ATPase activity and the affinity of the enzyme for Na+, K+, and ATP in membranes isolated from erythrocytes of hypertensive (with and without medication) and normotensive subjects. Subsequently, the active (ouabain-sensitive) sodium and potassium fluxes and their ratios have been determined after treatment of intact erythrocytes either with cold or with p-chloromercuribenzene-sulfonate (PCMBS). Finally, in view of a subsequent claim that the furosemide-sensitive, ouabain-insensitive cation fluxes would be greatly reduced in erythrocytes of patients with essential hypertension, we have determined these fluxes in choline chloride medium containing ouabain with and without furosemide. For none of these parameters has any significant difference between hypertensive and normotensive subjects been found except for a decrease in the ouabain-sensitive K+ influx after cold treatment in hypertensives. This is also true for the hypertensive subjects who had a known hypertensive parent. It is concluded that the results do not support a role of Na+-K+ activated ATPase or the furosemide-sensitive cation carrier in the pathogenesis of essential hypertension, and that ouabain-sensitive and furosemide-sensitive cation flux determinations in erythrocytes do not seem to be useful for the diagnosis of this condition.     

Renal oxidative stress in medullary thick ascending limbs produced by elevated NaCl and glucose

The effects of NaCl, glucose, and thyroid hormone on the production of superoxide (O2*-) within the renal medulla of Sprague-Dawley rats were examined. Responses of intracellular superoxide [O2*-]i in isolated medullary thick ascending limbs (mTALs) were studied using real-time fluorescent microscopy with measurement of the dehydroethidium (DHE) to ethidium (Eth) conversion ratio (Eth/DHE ratio unit). The results demonstrated that elevations of extracellular NaCl (from 152 to 252 mmol/L), D-glucose (from 5 to 25 mmol/L), and triiodo-thyronine (T3; 10 micromol/L) significantly increased [O2*-]i levels. Preincubation with superoxide scavenger 4,5-dihydroxy-1,3-benzene-disulfonic acid (1 mmol/L) significantly inhibited these responses. Stimulation with equamolar amounts of choline chloride or L-glucose failed to increase [O2*]i, indicating that these O2*- responses were not determined by changes in osmolality. The responses to NaCl, D-glucose, and T3 were abolished by pretreatment with the Na+/K+-ATPase pump inhibitor ouabain (4 mmol/L) and with Na+/H+ -exchanger inhibitor dimethylamiloride (100 micromol/L). We conclude that elevations of extracellular NaCl, D-glucose, or T3 levels can activate both the Na+/K+-ATPase pump and Na+/H+ exchanger in mTAL, which, in turn, is associated with increased intracellular concentrations of superoxide.     

Kinetic analysis of erythrocyte Na+-K+ pump and cotransport in essential hypertension

Alterations in red blood cell (RBC) Na+-K+ pump and Na+-K+ cotransport have been described in essential hypertension. We evaluated Na+-K+ pump and cotransport in 30 hypertensive and 26 normotensive subjects subdivided by race and family history of hypertension using an improved method to examine the kinetics of Na and K effluxes. RBCs were Na-loaded by the nystatin method to five different levels of internal Na with pump determined as ouabain-sensitive Na efflux and cotransport as furosemide-sensitive Na and K efflux. Two kinetic parameters were determined for both transport systems: the apparent affinity for Na (K0.5) and the velocity of efflux at saturating internal Na concentration (Vmax). Mean intracellular Na content in fresh RBCs (mmol/L cells) was higher in black hypertensive (12.6 +/- 1.8 mmol/L cells) and normotensive subjects (10.9 +/- 1.2 mmol/L cells) than in white hypertensive (8.7 +/- 1.0 mmol/L cells) or normotensive subjects (8.5 +/- 0.8 mmol/L cells). The Vmax and K0.5 for pump were not significantly different between study groups. The Vmax for cotransport was elevated in white hypertensive compared with normotensive subjects, but the K0.5 values were similar. Black normotensive and hypertensive subjects displayed a lower Vmax and increased K0.5 for cotransport compared with the white groups. A family history of hypertension had no influence on cotransport kinetics in blacks but did predict white normotensive and hypertensive subjects with low cotransport. The reduction in intracellular Na affinity for cotransport in black subjects may explain their higher intracellular Na in fresh RBCs.(ABSTRACT TRUNCATED AT 250 WORDS)     

高原红细胞增多症患者中性粒细胞[Ca2＋]i及NADPH氧化酶活性变化

目的 观察高原红细胞增多症（HAPC）患者外周血中性粒细胞[Ca2＋]i及NADPH氧化酶活性变化.方法 HAPC患者30例（HAPC组）,世代居住的健康者29例（健康组）,分离两组外周血中性粒细胞,两组细胞各添加fM-LP（终浓度为0、0.001、0.01、0.1、1、10 μmol/L）及PMA（终浓度为0、10、20、30、40、50 μmol/L）后,采用钙离子荧光探针（Fura-2/AM）法检测两组中性粒细胞内[Ca2＋]i;ELISA法检测中性粒细胞NADPH氧化酶活性.结果 fMLP终浓度为0.1、1、10 μmol/L时,健康组中性粒细胞[Ca2＋]i分别为（223.6 ±34.6）、（260.7 ±30.0）、（316.6 ±53.8） nmol/L;HAPC组分别为（203.2±25.6）、（235.5 ±35.9）、（278.1 ±47.1） nmol/L,两组比较,P＜0.05或＜0.01.fMLP终浓度为0.1、1、10 μmol/L时,健康组中性粒细胞NADPH氧化酶活性分别为（81.3±16.9）、（97.6±23.7）、（119.5 ±33.8）pmol/（10-6个细胞·30 min）;HAPC组分别为（72.0±16.9）、（83.6±15.3）、（102.9±26.3） pmol/（10-6个细胞·30min）,两组比较,P＜0.05或＜0.01.PMA终浓度为30、40、50 μmol/L时,健康组中性粒细胞[Ca2＋]i分别为（224.9±33.1）、（326.7 ±45.3）、（646.9 ±78.1） nmol/L;HAPC组分别为（205.5±26.3）、（293.9 ±52.6）、（567.9±103.1）nmol/L,两组比较,P ＜0.05或＜0.01.PMA终浓度为30、40、50 μmol/L时,健康组中性粒细胞NADPH氧化酶活性分别为（258.2±25.1）、（327.3 ±38.5）、（383.1±36.7）pmol/（10-6个细胞·30 min）;HAPC组分别为（213.8 ±36.3）、（291.3 ±50.5）、（337.2±36.0） pmol/（10-6个细胞·30 min）,两组比较,P＜0.01.结论 高原缺氧降低人外周血中性粒细胞NADPH活性及[Ca2＋]i浓度升高幅度.     

Tempol prevents altered K(+) channel regulation of afferent arteriolar tone in diabetic rat kidney

Experiments were performed to test the hypothesis that oxidative stress underlies the enhanced tonic dilator impact of inward-rectifier K(+) channels on renal afferent arterioles of rats with streptozotocin-induced diabetes mellitus. Sham and diabetic rats were left untreated or provided Tempol in their drinking water for 26±1 days, after which afferent arteriolar lumen diameter and its responsiveness to K(+) channel blockade were measured using the in vitro blood-perfused juxtamedullary nephron technique. Afferent diameter averaged 19.4±0.8 μm in sham rats and 24.4±0.8 μm in diabetic rats (P<0.05). The decrease in diameter evoked by Ba(2+) (inward-rectifier K(+) channel blocker) was 3 times greater in diabetic rats than in sham rats. Glibenclamide (K(ATP) channel blocker) and tertiapin-Q (Kir1.1/Kir3.x channel blocker) decreased afferent diameter in diabetic rats but had no effect on arterioles from sham rats. Chronic Tempol treatment prevented diabetes mellitus-induced increases in both renal vascular dihydroethidium staining and baseline afferent arteriolar diameter. Moreover, Tempol prevented the exaggeration of afferent arteriolar responses to Ba(2+), tertiapin-Q, and glibenclamide otherwise evident in diabetic rats. Preglomerular microvascular smooth muscle cells expressed mRNA encoding Kir1.1, Kir2.1, and Kir6.1. Neither diabetes mellitus nor Tempol altered Kir1.1, Kir2.1, Kir6.1, or SUR2B protein levels in renal cortical microvessels. To the extent that the effects of Tempol reflect its antioxidant actions, our observations indicate that oxidative stress contributes to the exaggerated impact of Kir1.1, Kir2.1, and K(ATP) channels on afferent arteriolar tone during diabetes mellitus and that this phenomenon involves posttranslational modulation of channel function.     

Reduction of erythrocyte (Na(+)-K+) ATPase activities in non-insulin-dependent diabetic patients with hyperkalemia.

To elucidate the mechanism of hyperkalemia in diabetic patients without renal failure, we investigated (Na(+)-K+) adenosine triphosphatase (ATPase) activity in erythrocyte membrane, erythrocyte Na+ and K+ content, and plasma endogenous digitalis-like substance in control subjects (n = 16) and non-insulin-dependent diabetes mellitus (NIDDM) patients (n = 62). NIDDM patients were divided into normokalemic patients (NKDM, n = 48) and hyperkalemic patients (HKDM, n = 14). There was no difference in plasma glucose or hemoglobin A1c (HbA1c) levels, plasma renin activity (PRA), and plasma aldosterone concentrations (PAC) between NKDM and HKDM patients. (Na(+)-K+)ATPase activities in NIDDM patients were significantly reduced compared with those in control subjects (0.336 +/- 0.016 mumol-inorganic phosphate [Pi]/mg protein/h, mean +/- SEM, P less than .05), and (Na(+)-K+)ATPase activities in HKDM patients (0.243 +/- 0.015 mumol Pi/mg protein/h) were significantly reduced compared with those in NKDM patients (0.295 +/- 0.008 mumol Pi/mg protein/h, P less than .01). Plasma K+ content had a significant negative correlation with (Na(+)-K+)ATPase activity in diabetic patients (r = -.365, P less than .01). Erythrocyte Na+ content had a significant negative correlation with (Na(+)-K+)ATPase activity in control subjects (r = -.619, P less than .05). There was no difference in plasma endogenous digitalis-like substance among the three groups. (Na(+)-K+)ATPase activity was not significantly correlated with plasma endogenous digitalis-like substance in control subjects and diabetic patients. These findings suggest that the reduction of (Na(+)-K+)ATPase activity, which was not related to plasma digitalis-like substance, may be partly responsible for hyperkalemia in diabetic patients.     

NADPH氧化酶在瘦素诱导肝星状细胞株HSC-T6产生活性氧中的作用及其机制

目的 研究NADPH氧化酶(NOX)是否参与瘦素诱导肝星状细胞(HSC)产生活性氧(ROS),并探讨其机制. 方法取对数生长期的HSC-T6细胞,随机分为9组:瘦素组、瘦素+ROS生成系统抑制剂[包括氯化二亚苯基碘嗡(DPI)、鱼藤酮、甲双吡丙酮、别嘌呤醇和吲哚美辛]组成的干预组、瘦素+JAK抑制剂AG490组成的干预组、正常对照组和阴性对照组.HSC-T6细胞经药物作用1、12、24 h后,荧光显微镜和(或)流式细胞术观察细胞内二氯荧光素强度来反应ROS水平;分光光度计检测NADPH的吸光度,以NADPH的消耗量表示NOX活性;逆转录聚合酶链反应检测Rac1和p22Phox的mRNA相对表达量.数据分析用单因素方差分析、SNK-q检验或秩和检验,P＜0.05为差异有统计学意义.结果 HSC-T6细胞加入瘦素(100 ng/ml)作用1 h后,荧光强度较正常对照组明显升高(92.91±4.19比27.56±6.27,P＜0.01);DPI(20 μmol/L)和AG490(50 μ mol/L)能抑制ROS的产生,荧光强度值分别为37.35±4.66和53.12±6.63,均低于瘦素组的92.91±4.19(q值分别为31.78和22.76,P值均＜0.01).瘦素作用HSC-T6细胞1 h后,NADPH的消耗量较正常对照组明显升高[(1.90±0.22)pmol·min-1·mg1比(0.76±0.06)pmol·min-1·mg-1,P＜0.05)],而作用12、24 h后的消耗量明显高于1 h时的消耗量(x2值均为7.54,P值均＜0.05);DPI及AG490干预能抑制瘦素诱导NOX活性的上调(q值分别为16.58和16.23,P值均＜0.05).瘦素作用12 h后,HSC-T6细胞内Racl和p22Phox的mRNA相对表达量明显高于正常对照组(分别为0.41±0.13比0.14±0.08和0.45±0.12比0.20±0.08,P值均＜0.05).结论 瘦素诱导HSC产生的ROS主要来源于NOX,其机制可能是瘦素通过JAK信号通路直接激活NOX,并通过上调NOX的亚基表达使NOX活性持续增高而产生大量ROS.     

大黄抑制近端小管和髓袢升支粗段小管Na~＋－K~＋ATP酶活性

在体内和体外实验中系统地观察了中药大黄对大鼠近端小管和髓袢升支粗段小管Ｎａ￣＋－ｋ￣＋ＡＴＰ酶活性的影响，发现大黄对此二节段肾小管Ｎａ￣＋－Ｋ￣＋ＡＴＰ酶均具有显著抑制作用，尤其是对髓袢升支粗段作用更为明显。大黄的作用随剂量增大而增强，５０ｍｇ／Ｌ大黄对髓袢升支粗段Ｎａ￣＋Ｋ￣＋ＡＴＰ酶活性的抑制率达４２．９％。体内应用大黄后，出现利钠、利尿效应。本实验结果进一步明确了大黄对残余肾肾小管高代谢的抑制作用。     

Membrane ion transport in erythrocytes of salt hypertensive Dahl rats and their F2 hybrids: the importance of cholesterol.

The possible association of salt hypertension and altered lipid metabolism with abnormalities of particular systems transporting sodium and potassium has been studied in erythrocytes of Dahl rats and their F2 hybrids fed a high-salt diet since weaning. Our attention was paid to the Na(+)-K+ pump, Na(+)-K+ cotransport and especially to passive membrane permeability for Na+ and Rb+ (Na+ and Rb+ leak), because the Na+ leak was found to be dependent on the genotype, age and salt intake of Dahl rats, whereas the Rb+ leak was suggested to be a potential marker of salt sensitivity in Dahl and Sabra rats. Young male Dahl salt-sensitive (SS/Jr) and salt-resistant (SR/Jr) rats kept on a low-salt (0.3% NaCl) or high-salt diet (8% NaCl) were used for the progenitor study. The subsequent genetic study was based on 135 young male SS/Jr x SR/Jr F2 hybrids fed a high-salt diet since weaning. Ouabain (5 mmol/l) and bumetanide (10 micromol/l) were used to distinguish the contribution of the Na(+)-K+ pump, Na(+)-K+ cotransport and passive membrane permeability to measured net Na+ fluxes and unidirectional Rb+ (K+) movements. Compared to normotensive SR/Jr animals, salt-loaded SS/Jr rats had higher blood pressure (BP), elevated erythrocyte Na+ content, and increased Na+ and Rb+ leaks together with enhanced Na+ and Rb+ transport mediated by the Na(+)-K+ pump and Na(+)-K+ cotransport system. Salt hypertensive Dahl rats were also characterized by elevated plasma levels of total cholesterol and triglycerides, which were positively associated with BP of F2 hybrids (r=0.27 and 0.24, p< 0.01). In F2 hybrids, mean arterial pressure correlated significantly with erythrocyte Na+ content (r=0.24, p<0.01) and ouabain-sensitive Na+ extrusion, but not with the passive membrane permeability for Na+ or Rb+ (r=-0.02 and 0.06, not significant). Both of the above-mentioned significant associations could partially be ascribed to the dependence of erythrocyte Na+ content and ouabain-sensitive Na+ extrusion on plasma cholesterol (r=0.18 and 0.21, p<0.05). Our results support the idea that abnormal lipid metabolism and/or altered Na+,K(+)-ATPase function play an important role in the pathogenesis of salt hypertension in salt-sensitive Dahl rats.     

Endothelin-1 stimulates arterial VCAM-1 expression via NADPH oxidase-derived superoxide in mineralocorticoid hypertension

Although hypertension is a major risk factor for atherosclerosis, its underlying mechanisms remain to be delineated. We have recently reported that both endothelin-1 (ET-1) and vascular cellular adhesion molecule-1 (VCAM-1) levels, key early markers of atherosclerosis, are significantly elevated in carotid arteries of deoxycorticosterone acetate (DOCA)-salt hypertensive rats, a model known for its suppressed plasma renin levels. This study tested the hypothesis that ET-1 augments arterial VCAM-1 expression through NADPH oxidase-derived superoxide (O2-). Carotid arteries of DOCA-salt or sham-operated rats were transduced ex vivo with extracellular superoxide dismutase (EC-SOD), dominant negative HA-tagged N17Rac1 that inhibits Rac1, the small GTPase component of NADPH oxidase, or beta-galactosidase (beta-gal) reporter gene (5x10(10) plaque formation units [pfu]/mL), and the effect of transgene expression on O2- and VCAM-1 levels was assayed 24 hours afterward. The arterial activity of NADPH oxidase but not xanthine oxidase was significantly higher in DOCA-salt than in sham rats, which was abolished by the selective ETA receptor antagonist ABT-627 (3x10(-8) mol/L), NADPH oxidase inhibitor apocynin (10(-4) mol/L), or dominant negative Rac1 gene transfer. The levels of O2- and VCAM-1 were significantly increased in arteries of DOCA-salt rats, an effect that was ameliorated after EC-SOD or dominant negative Rac1 but not beta-gal reporter gene transfer. ABT-627 and apocynin also significantly reduced elevated VCAM-1 levels in ET-1-treated arteries of normal rats and arteries of DOCA-salt rats. The results of this study indicate that ET-1 stimulates arterial VCAM-1 expression by producing O2- from an ETA receptor/NADPH oxidase pathway in low-renin mineralocorticoid hypertension.     

Myocardial inositol and sodium in diabetes.

Although inhibition of Na(+)-K+ ATPase has been described in the diabetic heart, K+ loss from myocardium has not been observed in a canine model of mild diabetes. The finding of tissue Na+ accumulation and a potential relation to alteration of left ventricular inositol as observed in other tissues in diabetes form the basis of this investigation. Diabetes was induced with alloxan in three groups of male mongrel dogs who were studied after 1 yr. In the initial experiment the tissue compartment volumes, determined with intravenous 51Cr EDTA as a marker, were found to be normal. Calculated cell sodium was increased to 32.8 +/- 2.6 mEq/kg cell H2O vs 18.7 +/- 1.1 in controls (p < 0.01). Cell potassium in diabetes was normal. In the second group, myocardial polyols were analyzed by gas-liquid chromatography. Inositol was diminished in diabetes to 0.61 +/- 23 microM/g of left ventricle, vs the respective control levels of 1.9 +/- 0.57 microM/g (p < 0.02). Sorbitol concentration was unaltered. Left ventricular sodium increments were not associated with altered tissue calcium. In group III the hypothesis that inhibition of Na(+)-K+ ATPase in diabetes might not elicit the expected alteration of K+ transport was assessed during intracoronary infusion of acetyl strophanthidin. No difference in cation responses from control was observed. It is postulated that a change in the conformation of Na(+)-K+ ATPase, with high affinity sodium binding sites facing the intracellular compartment, may render sodium less releasable from cell membrane.     

血浆同型半胱氨酸与2型糖尿病外周神经病变的相关性

目的 探讨血浆总同型半胱氨酸浓度与糖尿病外周神经病变的关系.方法 入选2型糖尿病患者227例,进行横断面研究.用临床表现及肌电图诊断外周糖尿病神经病变,并测定血浆同型半胱氨酸水平及与糖尿病神经病变相关或可能影响血浆同型半胱氨酸水平的指标.结果 糖尿病外周神经病变患者80例,糖尿病无神经病变者147例.糖尿病神经病变组血浆总同型半胱氨酸水平(12.6±3.6)μmol/L,高于糖尿病非神经病变组(8.2±0.9)μmol/L(P＜0.01).在校正外周神经病变传统危险因素(糖尿病病程、糖化血红蛋白)及高同型半胱氨酸浓度的影响因素(年龄、性别、血清叶酸和维生素B12、肾功能状态和双胍类使用)后,同型半胱氨酸与糖尿病神经病变仍相关[OR1.15(1.02～1.28),P＜0.05].在校正每单位上述混杂因素增加后,每增加4.0 μmol/L的血浆同型半胱氨酸也与神经病变发生密切相关[OR 1.17(0.94～1.33),P＜0.05].结论 高血浆总同型半胱氨酸浓度与糖尿病神经病变的发生相关,为糖尿病外周神经病变的独立危险因素.

Abstract：

Objective To explore the relationship between plasma homocysteine levels and diabetic peripheral neuropathy (DPNP). Methods A crossectional analysis was conducted on 227 patients with type 2 diabetes. Peripheral neuropathy was confirmed using electromyography (EMG). The risk factors possibly associated with diabetic neuropathy or plasma homocysteine levels were analyzed in relation to likelihood of occurrence of DPNP. Results Eighty patients with neuropathy and 147 patients without neuropathy were included. Plasma homocysteine levels were significantly higher in patients with diabetic neuropathy [( 12. 6 ± 3.6 ) μmol/ L] than without diabetic neuropathy [( 8. 2 ± 0. 9 ) μmol/L] ( P ＜0. 001 ), and the relationship remained significant after adjusting for duration of diabetes, glycosylated hemoglobin A1c (HbA1c), age, renal status, serum folate acid and vitamin B12, and metformin [OR 1.15( 1.02-1.28 ) ,P ＜ 0. 05]. In addition, per increase of 4. 0 μmol/L plasma homocysteine was closely related to the occurrence of neuropathy after controlling for per unit increase of other confounding factors [OR 1.17(0. 94-1.33), P ＜ 0. 05]. Conclusions Hyperhomocysteinemia was an independent risk factor for the occourence of diabetic peripheral neuropathy.     

糖尿病肾病相关危险因素分析（英文）

目的：探讨影响糖尿病肾病的相关危险因素。方法：入选明确诊断2型糖尿病患者238例,根据尿微量白蛋白/尿肌酐的比值（UACR）分为糖尿病无肾病组（糖尿病1组,90例）,早期糖尿病肾病组（糖尿病2组,73例）,临床糖尿病肾病组（糖尿病3组,75例）,收集所有患者的临床资料,并检测餐前及餐后2h血糖（FBG、2hPB）,血脂、尿酸（UA）、纤维蛋白原（Fg）、糖化血红蛋白（HbA1c）等生化指标,并分析其与糖尿病肾病的相关性。结果：糖尿病1组、糖尿病2组、糖尿病3组的糖尿病病程[（7.25±6.29）年比（10.25±7.67）年比（13.53±7.82）年]、FBG[（8.46±2.52）mmol/L比（9.52±3.38）mmol/L比（10.82±3.30）mmol/L]、2hPB[（18.40±5.64）mmol/L比（20.27±5.94）mmol/L比（22.59±6.14）mmol/L]、HbA1c[（7.96±1.65）%比（8.60±1.76）%比（9.55±2.09）%]、甘油三酯[（1.72±0.86）mmol/L比（2.34±1.87）mmol/L比（3.16±1.85）mmol/L]、Fg[（3.49±0.93）g/L比（3.88±1.21）g/L比（4.99±2.10）g/L]、UA[（295.42±52.34）μmol/L比（324.18±96.29）μmol/L比（351.23±56.88）μmol/L]水平逐渐显著升高（P〈0.05～〈0.01）。Lo-gistic逐步回归分析显示,糖尿病病程、HbA1c、TG、Fg、UA是糖尿病肾病的危险因素（优势比=1.008～1.910,P〈0.01～〈0.001）。结论：糖尿病病程、血糖、血脂、血尿酸和纤维蛋白原是糖尿病肾病的危险因素;尿微量白蛋白/尿肌酐比值升高反映糖尿病人病情的进展,测定它有助于糖尿病的防治。     

血清胆红素与糖尿病周围神经病变相关性研究

目的探讨血清胆红素与糖尿病周围神经病变（DPN）的关系。方法收集110例2型糖尿病（T2DM）并发周围神经病变患者（DPN组）、220例单纯T2DM患者（DM组）和健康体检者278名（Con组）的血清胆红素等临床资料,并进行Logistic回归分析,筛选DPN的危险因素。对间接胆红素（IBIL）进行进一步的分析。结果（1）低血清INL、病程长、LDLC升高是DPN的危险因素。（2）协方差分析表明,控制尿白蛋白（UA1b）等因素后,DPN组的INL水平[（9．7±0．6）μmol／L]仍然明显低于DM组[（12．0±0．6）μmol／L]和Con组[（11．4±0．3）μmol／L]。结论低血清IBIL与DPN密切相关,是DPN发病相关因素之一。     

Functional interactions between oxidative stress, membrane Na(+) permeability, and cell volume in rat hepatoma cells

BACKGROUND & AIMS: Oxidative stress leads to a rapid initial loss of liver cell volume, but the adaptive mechanisms that serve to restore volume have not been defined. This study aimed to evaluate the functional interactions between oxidative stress, cell volume recovery, and membrane ion permeability. METHODS: In HTC rat hepatoma cells, oxidative stress was produced by exposure to H(2)O(2) or D-alanine plus D-amino acid oxidase (40 U/mL). RESULTS: Oxidative stress resulted in a rapid decrease in relative cell volume to 0.85 +/- 0.06. This was followed by an approximately 100-fold increase in membrane cation permeability and partial volume recovery to 0.97 +/- 0.05 of original values. The volume-sensitive conductance was permeable to Na(+) approximately K(+) > Tris(+), and whole-cell current density at -80 mV increased from -1.2 pA/pF at 10(-5) mol/L H(2)O(2) to -95.1 pA/pF at 10(-2) mol/L H(2)O(2). The effects of H(2)O(2) were completely inhibited by dialysis of the cell interior with reduced glutathione, and were markedly enhanced by inhibition of glutathione synthase. CONCLUSIONS: These findings support the presence of dynamic functional interactions between cell volume, oxidative stress, and membrane Na(+) permeability. Stress-induced Na(+) influx may represent a beneficial adaptive response that partially restores cell volume over short periods, but sustained cation influx could contribute to the increase in intracellular [Na(+)] and [Ca(2+)] associated with cell injury and necrosis.     

Medullary thick ascending limb buffer vasoconstriction of renal outer-medullary vasa recta in salt-resistant but not salt-sensitive rats

We have demonstrated previously that paracrine signaling occurs between medullary thick ascending limb (mTAL) and the contractile pericytes of outer-medullary vasa recta (VR), termed "tubular-vascular cross-talk." The aim of the current study was to determine whether tubular-vascular cross-talk has a functional effect on vasoconstrictor responses to angiotensin II and to determine whether this is altered in the Dahl salt-sensitive (SS) rat. Studies were performed on salt-resistant consomic SS.13 Brown Norway (BN) and SS rats using a novel outer medullary tissue strip preparation in which freshly isolated VRs within VR bundles were perfused either alone or in combination with nearby mTAL. In VRs from SS.13 (bn) rats, angiotensin II (1 μmol/L) increased VR bundle intracellular Ca(2+) concentration 19 ± 9 nmol/L (n=8) and reduced focal diameter in perfused VRs by -20 ± 7% (n=5). In the presence of nearby mTAL, however, VR bundle intracellular Ca(2+) concentration (-9 ± 8 nmol/L; n=8) and VR diameter (-1 ± 4%, n=7) in SS.13(bn) rats were unchanged by angiotensin II. In contrast, in Dahl SS rats, angiotensin II resulted in rapid and sustained increase in VR bundle intracellular Ca(2+) concentration (89 ± 48 nmol/L, n=7; 50 ± 24%, n=8) and a reduction in VR diameter of (-17 ± 7%, n=7; -11 ± 4%, n=5) in both isolated VRs and VRs with nearby mTAL, respectively. In VRs with mTAL from SS13(bn) rats, inhibiton of purinergic receptors resulted in an increase in VR bundle intracellular Ca(2+) concentration, indicating that purinergic signaling buffers vasoconstriction. Importantly, our in vitro data were able to predict medullary blood flow responses to angiotensin II in SS and SS.13(bn) rats in vivo. We conclude that paracrine signaling from mTAL buffers angiotensin II vasoconstriction in Dahl salt-resistant SS.13(bn) rats but not SS rats.     

Angiotensin II-NAD(P)H oxidase-stimulated superoxide modifies tubulovascular nitric oxide cross-talk in renal outer medulla

The source of superoxide (O2*-) production and cell-to-cell interactions of O2*- and nitric oxide (NO) in response to angiotensin II (AngII) were studied by fluorescence microscopic techniques to image rat renal outer medullary microtissue strips. Changes in intracellular O2*- were determined by dihydroethidium-ethidium ratios, and NO was determined with 4,5-diaminofluorescein diacetate. AngII (1 micromol/L) significantly increased O2*- in the isolated, medullary thick ascending limb (mTAL). These responses were inhibited by the superoxide dismutase mimetic 4-hydroxytetramethylpiperidine-1-oxyl (TEMPOL) and by the NAD(P)H oxidase inhibitors diphenylene iodonium and apocynin. AngII did not increase O2*- in either pericytes of isolated, intact vasa recta (VR) or pericytes of VR with a disrupted endothelium, even when surrounded by mTAL. However, AngII did increase O2*- when the tissue strips were preincubated with the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO), indicating that cross-talk of O2*- from mTAL to the VR occurred but was normally inhibited by NO. Also, tissue O2*- reduction by TEMPOL increased the diffusion of NO from mTAL to the pericytes, indicating that cross-talk of NO from the mTAL to the VR is also inhibited by O2*-. We conclude that AngII stimulates O2*- production in mTAL via the NAD(P)H oxidase pathway and that interactions of O2*- and NO ultimately determine the effectiveness of in situ free-radical cross-talk between the mTAL and the VR.     

阿托伐他汀对同型半胱氨酸所诱导内皮祖细胞功能损伤的保护作用

目的:探讨同型半胱氨酸(homocysteine,Hcy)诱导小鼠骨髓内皮祖细胞(endothelial progenitor cells,EPCs)功能损伤的氧化应激机制及阿托伐他汀的拮抗作用。方法:密度梯度离心法获取小鼠骨髓单个核细胞,培养7 d后收集贴壁细胞,FITC-UEA-1荧光染色鉴定EPCs。EPCs与不同浓度Hcy(0μmol/L,50μmol/L,500μmol/L)共孵育24 h或分别经不同浓度的阿托伐他汀(0.1μmol/L,1μmol/L,10μmol/L)预孵育0.5 h后,再加入500μmol/LHcy共孵育24 h。用MTT比色法,改良Boyden小室、黏附能力测定和体外血管生成试剂盒,分别观察EPCs的增殖能力、迁移能力、黏附能力和体外血管生成能力。荧光探针H2DCF-DA法检测细胞内活性氧水平,光泽精化学发光法检测NADPH氧化酶活性,硝酸还原酶法测定细胞培养液中一氧化氮(NO)含量,RT-PCR法测定eNOS基因表达。结果:Hcy诱导EPCs增殖、迁移、黏附和体外血管生成功能下降,活性氧的产生及NADPH氧化酶的活性增加,eNOS基因表达及细胞培养液中NO含量减少,与无Hcy处理组相比有明显差异(P0.05或P0.01)。与500μmol/L Hcy组相比,阿托伐他汀预处理可呈剂量依赖性地拮抗Hcy诱导的上述改变(P0.05或P0.01)。结论:Hcy可能通过激活NADPH氧化酶,诱导EPCs活性氧的产生及降低eNOS基因表达和NO水平,导致EPCs增殖、迁移、黏附和体外血管生成功能下降。阿托伐他汀部分拮抗Hcy的作用。     

罗格列酮联合阿托伐他汀对单核细胞分泌肿瘤坏死因子α的影响

目的 研究罗格列酮联合阿托伐他汀干预对无糖尿病的急性冠脉综合征（ACS）患者外周血单核细胞分泌肿瘤坏死因子α（TNF-α）的影响。方法 分离无糖尿病的ACS患者外周血单核细胞,设置对照组（等容积的二甲基亚砜）、阿托伐他汀（1 μmol/L）组、罗格列酮（1 μmol/L）组及二者联合组（阿托伐他汀1 μmol/L加罗格列酮1 μmol/L组） 4个组,分别与所分离的外周血单核细胞共同孵育24 h后,用夹心酶联免疫吸附测定法检测细胞培养上清液TNF-α,用逆转录聚合酶链反应（RT-PCR）测定TNF-α mRNA的表达。结果 与对照组相比较,阿托伐他汀组、罗格列酮组及联合组对无糖尿病ACS患者外周血单核细胞分泌TNF-α［分别为(229±24)ng/L、(236±28)ng/L、(159±29)ng/L vs (306±40)ng/L,均P<0.05］及TNF-α mRNA的相对半定量吸光值（A）比值（分别为0.35±0.12,0.39±0.11,0.26±0.06 vs 0.78±0.14,均P<0.05）均降低,且罗格列酮联合阿托伐他汀组比阿托伐他汀组、罗格列酮组降低更显著（均P<0.05）。结论 阿托伐他汀和罗格列酮都可通过降低无糖尿病的ACS患者外周血单核细胞产生分泌TNF-α,发挥阿托伐他汀和罗格列酮的抗炎作用,且二者联合干预具有协同作用,防治效果更佳。