Infusion of the beta-adrenergic blocker esmolol attenuates myocardial dysfunction in septic rats

OBJECTIVE: Since beta-blocker therapy is known to be effective in patients with an injured heart, such as infarction, we designed the present study to examine the protective effects of infusion of the beta1-selective blocker esmolol on myocardial function in peritonitis-induced septic rats using an isolated working heart preparation. DESIGN: Randomized animal study. SETTING: University research laboratory. SUBJECTS: Thirty-one rats treated with cecal ligation and perforation to evoke peritonitis. INTERVENTIONS: After cecal ligation and perforation, rats were randomly allocated to the control group (normal saline 2 mL/hr, n = 11), low-dose esmolol group (10 mg/kg/hr, n = 10), or high-dose esmolol group (20 mg/kg/hr, n = 10). After obtaining blood samples for measurement of arterial lactate and tumor necrosis factor-alpha at 24 hrs, we assessed cardiac output, myocardial oxygen consumption, and cardiac efficiency (cardiac output x peak systolic pressure/myocardial oxygen consumption) at various preloads in an isolated perfused heart preparation. MEASUREMENTS AND MAIN RESULTS: Esmolol infusion did not cause an elevation of arterial lactate levels but reduced tumor necrosis factor-alpha concentrations vs. the control group (p < .05). Both cardiac output and cardiac efficiency in the esmolol-treated rats were significantly higher throughout the study periods vs. the control group (p < .05). CONCLUSIONS: Esmolol infusion in sepsis improved oxygen utilization of myocardium and preserved myocardial function.     

Propofol attenuates high glucose‐induced superoxide anion accumulation in human umbilical vein endothelial cells

Perioperative hyperglycemia is a common clinical metabolic disorder. Hyperglycemia could induce endothelial apoptosis, dysfunction, and inflammation, resulting in endothelial injury. Propofol is a widely used anesthetic drug in clinical settings. Our previous studies indicated that propofol attenuated high glucose‐induced endothelial apoptosis, dysfunction, and inflammation via inhibiting reactive oxygen species (ROS) accumulation. However, the mechanisms by which propofol reduces high glucose‐induced endothelial ROS accumulation are still obscure. In this study, we examined how propofol attenuates high glucose‐induced endothelial ROS accumulation. Compared with 5 mm glucose treatment, 15 mm glucose upregulated the expression of pin‐1, phosphatase A2 (PP2A), p66^shc and mitochondrial p66^shc expression, increased p66^shc‐Ser³⁶ phosphorylation, and accumulation. More importantly, although propofol had no effect on 15 mm glucose‐induced p66^shc‐Ser³⁶ phosphorylation and pin‐1 expression, propofol could downregulated PP2A expression and p66^shc expression in whole‐cell and mitochondrion, resulting in the reduction of accumulation. Moreover, we demonstrated that the antioxidative effect of propofol was similar to that of calyculin A, an inhibitor of PP2A. In contrast, FTY720, an activator of PP2A, antagonized the effect of propofol. Our data indicated that the antioxidative effect of propofol was achieved by downregulating PP2A expression, resulting in the inhibition of p66^shc‐Ser³⁶ dephosphorylation and mitochondrial p66^shc expression.     

Thoracic epidural anesthesia time-dependently modulates pulmonary endothelial dysfunction in septic rats

Introduction  

Increasing evidence indicates that epidural anesthesia improves postoperative pulmonary function. The underlying mechanisms, however, remain to be determined. Because pulmonary nitric oxide has been identified to play a critical role in pulmonary dysfunction in sepsis, we hypothesized that thoracic epidural anesthesia (TEA) modulates endothelial dysfunction via a nitric oxide-dependent pathway.     

Adenovirus-mediated overexpression of extracellular superoxide dismutase improves endothelial dysfunction in a rat model of hypertension

Gene transfer may be appropriate for therapeutic protocols targeted at the vascular endothelium. Endothelial dysfunction is the principal phenotype associated with atherosclerosis and hypertension. Oxidative stress has been implicated in the development of endothelial dysfunction. We have explored the ability of overexpressing anti-oxidant genes (superoxide dismutases; SODs) in vitro and in vivo to assess their potential for reversing endothelial dysfunction in a rat model, the stroke-prone spontaneously hypertensive rat (SHRSP). Western blotting and immunofluorescence assays in vitro showed efficient overexpression of MnSOD and ECSOD with respect to localisation to the mitochondria and extracellular surface, respectively. Transgene functional activity was quantified with SOD activity assays. MnSOD and ECSOD overexpression in intact SHRSP vessels in vivo led to endothelial and adventitial overexpression. Pharmacological assessment of transduced vessels following in vivo delivery by basal NO availability quantification demonstrated that the "null" adenovirus and MnSOD adenovirus did not significantly increase NO availability. However, AdECSOD-treated carotid arteries showed a significant increase in NO availability (1.91 +/- 0.04 versus 0.75 +/- 0.08 g/g, n = 6, P = 0.029). In summary, efficient overexpression of ECSOD, but not MnSOD in vivo, results in improved endothelial function in a rat model of hypertension and has important implications for the development of endothelial-based vascular gene therapy.     

1大鼠血管内皮功能障碍及胰岛素抵抗与高脂饮食的关系

目的：观察高脂饮食大鼠胰岛素抵抗的发生以及血管内皮功能的变化。 方法：实验于2006-05/06在东南大学实验动物中心完成。选用健康SD雄性大鼠16只,体质量150～180g,随机数字表法分为正常对照组和高脂饮食组,每组8只。正常对照组用普通饲料（成分：米糠80g,玉米粉500g,黄豆粉300g,骨粉30g,维生素13g,矿物质67g）喂养,高脂饮食组用高脂饲料（葵花油325g,玉米粉254g,全脂奶粉230g,米糠51g,鸡蛋30g,维生素13g,矿物质67g,骨粉30g,混合制成1000g）喂养4周。观察高脂饮食对大鼠空腹血糖、空腹胰岛素、胰岛素敏感指数、胰岛素抵抗指数、口服葡萄糖耐量试验、体质量、血浆内皮素1和血清一氧化氮的影响,以免疫组织化学方法检测血管内皮细胞内皮素1、内皮型一氧化氮合酶蛋白的表达。 结果：纳入大鼠16只均进入结果分析。①4周后高脂饮食组大鼠空腹胰岛素、胰岛素抵抗指数、体质量、血浆内皮素1及血管内皮细胞内皮素1阳性细胞数均明显高于正常对照组[（27.50±2.15）,（14.30±1.89）mIU/L,P〈0.01;（6.60±1.26）,（3.28±0.57）,P〈0.01;（332.69±15.85）,（312.38±16.37）g,P〈0.05;（77.82±6.28）,（64.72±5.42）ng/L,P〈0.01;（47.50±2.51）,（32.47±3.44）,P〈0.01]。②高脂饮食组大鼠胰岛素敏感指数、血清一氧化氮及血管内皮型一氧化氮合酶阳性细胞数均明显低于正常对照组[（-4.99±0.17）,（-4.29±0.19）;（46.50±3.08）,（54.63±5.58）μmol/L;（48.17±3.55）,（55.50±3.15）,P〈0.01]。③4周后口服葡萄糖耐量试验高脂饮食组在30,60,120min血糖值均高于正常对照组,差异有显著性意义[（8.71±0.63）,（7.90±0.53）mmol/L,P〈0.05;（9.51±0.45）,（7.28±0.43）mmol/L,P〈0.01;（6.58±0.48）,（5.80±0.58）mmol/L,P〈0.05）。 结论：高脂饮食可致大鼠胰岛素抵抗和血管内皮功能障碍,血脂代谢障碍是促成胰岛素抵抗的形成和血管内皮功能障碍的主要危险因素之一。     

Simvastatin improves diabetes-induced coronary endothelial dysfunction

3-Hydroxy-3-methylglutaryl CoA reductase inhibitors decrease cardiovascular morbidity in diabetic patients, but the mechanism is unclear. We studied the actions of simvastatin (SIM) in enhancing NO bioavailability and reducing oxidative stress in coronary vessels from diabetic rats and in rat coronary artery endothelial cells (RCAEC) exposed to high glucose. Coronary arteries isolated from diabetic rats showed decreases in acetylcholine (ACh)-mediated maximal relaxation from 81.0 +/- 4.5% in controls to 43.5 +/- 7.6% at 4 weeks and 22.3 +/- 0.6% at 10 weeks of diabetes. This effect was associated with oxidative stress in coronary vessels as shown by dichlorofluorescein (DCF) imaging and nitrotyrosine labeling. Diabetes also reduced trans-coronary uptake of [(3)H]l-arginine. Supplemental l-arginine (50 mg/kg/day p.o.) did not improve coronary vasorelaxation to ACh. However, SIM treatment (5 mg/kg/day subcutaneously) improved maximal ACh relaxation to 65.8 +/- 5.1% at 4 weeks and 47.1 +/- 3.9% at 10 weeks. Coronary arteries from rats treated with both SIM and l-arginine demonstrated the same maximal relaxation to ACh (66.1 +/- 3%) as SIM alone. Mevalonate and l-NAME (N(omega)-nitro-l-arginine methyl ester hydrochloride) inhibited the response to ACh in SIM-treated diabetic rats. Coronary arteries from all groups relaxed similarly to sodium nitroprusside. SIM increased endothelial NO synthase protein levels and blocked diabetes-induced increases in DCF and nitrotyrosine labeling in diabetic coronary vessels. SIM treatment restored normal NO levels in media from high-glucose-treated RCAEC and plasma of diabetic rat. Treatment with SIM or the NADPH oxidase inhibitor apocynin also blocked high-glucose-induced increases in reactive oxygen species and superoxide formation in RCAEC. Taken together, these data suggest that SIM improves diabetes-induced coronary dysfunction by reducing oxidative stress and increasing NO bioavailability.     

大鼠血管内皮功能障碍及胰岛素抵抗与高脂饮食的关系

目的:观察高脂饮食大鼠胰岛素抵抗的发生以及血管内皮功能的变化。方法:实验于2006-05/06在东南大学实验动物中心完成。选用健康SD雄性大鼠16只,体质量150～180g,随机数字表法分为正常对照组和高脂饮食组,每组8只。正常对照组用普通饲料(成分:米糠80g,玉米粉500g,黄豆粉300g,骨粉30g,维生素13g,矿物质67g)喂养,高脂饮食组用高脂饲料(葵花油325g,玉米粉254g,全脂奶粉230g,米糠51g,鸡蛋30g,维生素13g,矿物质67g,骨粉30g,混合制成1000g)喂养4周。观察高脂饮食对大鼠空腹血糖、空腹胰岛素、胰岛素敏感指数、胰岛素抵抗指数、口服葡萄糖耐量试验、体质量、血浆内皮素1和血清一氧化氮的影响,以免疫组织化学方法检测血管内皮细胞内皮素1、内皮型一氧化氮合酶蛋白的表达。结果:纳入大鼠16只均进入结果分析。①4周后高脂饮食组大鼠空腹胰岛素、胰岛素抵抗指数、体质量、血浆内皮素1及血管内皮细胞内皮素1阳性细胞数均明显高于正常对照组[(27.50±2.15),(14.30±1.89)mIU/L,P<0.01;(6.60±1.26),(3.28±0.57),P<0.01;(332.69±15.85),(312.38±16.37)g,P<0.05;(77.82±6.28),(64.72±5.42)ng/L,P<0.01;(47.50±2.51),(32.47±3.44),P<0.01]。②高脂饮食组大鼠胰岛素敏感指数、血清一氧化氮及血管内皮型一氧化氮合酶阳性细胞数均明显低于正常对照组[(-4.99±0.17),(-4.29±0.19);(46.50±3.08),(54.63±5.58)μmol/L;(48.17±3.55),(55.50±3.15),P<0.01]。③4周后口服葡萄糖耐量试验高脂饮食组在30,60,120min血糖值均高于正常对照组,差异有显著性意义[(8.71±0.63),(7.90±0.53)mmol/L,P<0.05;(9.51±0.45),(7.28±0.43)mmol/L,P<0.01;(6.58±0.48),(5.80±0.58)mmol/L,P<0.05)。结论:高脂饮食可致大鼠胰岛素抵抗和血管内皮功能障碍,血脂代谢障碍是促成胰岛素抵抗的形成和血管内皮功能障碍的主要危险因素之一。     

糖尿病大鼠股骨头血管内皮功能障碍的变化

背景:糖尿病骨病的并发症起病复杂,骨组织血管内皮病变可能是造成的一个重要原因.目的:探讨糖尿病对大鼠股骨头内皮功能障碍的影响.方法:将60只大鼠随机等分为对照组和糖尿病组,糖尿病组大鼠腹腔注射链脲佐菌素建立糖尿病模型.结果与结论:造模15周时,与对照组相比,糖尿病组大鼠股骨头出现骨质疏松显微结构改变,血清一氧化氮水平明显降低,血浆内皮素1水平明显升高,糖尿病组股骨头凝血因子Ⅷ表达明显减少(P < 0.01),提示糖尿病前期就出现内皮功能障碍.微血管增生,糖尿病诱发内皮功能障碍及相互作用与大鼠股骨头功能减退有关.     

Adrenomedullin reduces vascular hyperpermeability and improves survival in rat septic shock

Objective Current therapies of sepsis and septic shock require administration of a large volume of fluid to maintain hemodynamic stability. The vasoregulatory peptide adrenomedullin has been shown to prevent the transition to the fatal hypocirculatory septic state by poorly understood mechanisms. We tested the hypothesis that therapeutic administration of adrenomedullin would reduce vascular hyperpermeability, thereby contributing to improved hemodynamics and survival. Design Prospective randomized controlled animal study. Subjects Male Sprague–Dawley rats (270 g). Interventions We used 4.8 × 10³ U/kg of Staphylococcus aureus α-toxin, a pore-forming exotoxin, to induce vascular leakage and circulatory shock in rats. The infusion rate was 24 μg/kg per hour. Adrenomedullin was started 1 h after α-toxin administration. Measurement and results Infusion of α-toxin in rats induced cardiocirculatory failure resulting in a 6-h mortality of 53%. α-Toxin provoked massive vascular hyperpermeability, which was indicated by an enrichment of Evans blue dye albumin in the tissues of lung, liver, ileum and kidney. Plasma fluid loss led to a significant hemoconcentration. Hemodynamic impairment observed after α-toxin infusion was closely correlated to vascular hyperpermeability. Therapeutic administration of 24 μg/kg per hour adrenomedullin reduced 6-h mortality from 53% to 7%. Stabilization of the endothelial barrier by adrenomedullin was indicated by reduced extravasation of albumin and plasma fluid and may have contributed to hemodynamic improvement. Conclusions These data suggest that adrenomedullin-related reduction of vascular hyperpermeability might represent a novel and important mechanism contributing to the beneficial effects of this endogenous vasoregulatory peptide in sepsis and septic shock. Electronic supplementary material The online version of this article () contains supplementary material, which is available to authorized users. Bettina Temmesfeld-Wollbrück and Bernhard Brell contributed equally to this study     

Hypercholesterolemia increases endothelial superoxide anion production.

Indirect evidence suggests accelerated degradation of endothelium-derived nitric oxide (ENDO) by superoxide anion (O2-) in hypercholesterolemic vessels (HV). To directly measure O2- production by normal vessels (NV) and HV, we used an assay for O2- based on the chemiluminescence (CL) of lucigenin (L). HV (1 mo cholesterol-fed rabbits) produced threefold more O2- than NV (1.47 +/- 0.20 nM/mg tissue/min, n = 7 vs. 0.52 +/- 0.05 nmol/mg tissue/min, n = 8, P < 0.001). Endothelial removal increased O2- production in NV (0.73 +/- 0.08, n = 6, P < 0.05), while decreasing it in HV (0.76 +/- 0.15, n = 5, P < 0.05). There was no difference between denuded HV and denuded NV. Oxypurinol, a noncompetitive inhibitor of xanthine oxidase, normalized O2- production in HV, but had no effect in NV. In separate isometric tension studies treatment with oxypurinol improved acetylcholine induced relaxations in HV, while having no effect on responses in normal vessels. Oxypurinol did not alter relaxations to nitroprusside. Thus, the endothelium is a source of O2- in hypercholesterolemia probably via xanthine oxidase activation. Increased endothelial O2- production in HV may inactivate endothelium-derived nitric oxide and provide a source for other oxygen radicals, contributing to the early atherosclerotic process.     

Circulating endothelial cells and endothelial progenitors as surrogate biomarkers in vascular dysfunction

An increase in the number of circulating endothelial cells (CECs) and of bone marrow derived endothelial progenitors (CEPs) in the peripheral blood (PB) is normally associated with vascular injury, repair, and neovascularization. These cells rarely exist in the PB of healthy individuals. Therefore, when they are present in the PB of individuals, their phenotypes and quantity in the PB may serve as surrogate diagnostic or prognostic parameters of vascular injury and/or as an indication of tumor growth. An elevated level of CEPs may suggest an ongoing repair of ischemic vascular injuries and/or angiogenesis. Recently, more advanced techniques for CEC isolation and CEP enumeration have become available. In particular, immunobeads isolation and fluorescence-activated cell sorting (FACS) techniques have been employed with success in evaluation of vascular dysfunctions. Therefore, CECs and CEPs may serve as potential surrogate markers for monitoring various vascular diseases, which could help to determine pathological process and clinical treatment. In this article, we will present an overview of CECs and CEPs by discussing their origins, reviewing methodologies adapted to the measurement of rare events, describing pathological situations associated with CECs/CEPs, and correlating them with a broad spectrum of disease processes.     

From ST segments to endothelial pathophysiology: hypercholesterolemia and endothelial superoxide production

As a young medical resident, I encountered a patient suffering from spontaneous coronary vasospasm and was puzzled by these dramatic alterations in vasomotion. This encounter piqued my interest in understanding the drivers of vascular reactivity. In a paper published in the JCI, my colleagues and I revealed a role for superoxide production in the vascular dysfunction associated with hypercholesterolemia. Subsequent work by our group and others has unveiled complex associations between ROS generation and vascular disease. While a second-year internal medicine resident on the Duke coronary care unit in the 1970s, I admitted a young lady who was having repeated episodes of chest pain and profound ST-segment elevation on her electrocardiogram. During several of these episodes, she developed ventricular fibrillation that required cardioversion. An emergency cardiac catheterization revealed that her coronary arteries were overtly normal, but her left anterior descending coronary artery spontaneously developed spasm to the point of closure. Thankfully, these episodes eventually resolved. She obviously had variant angina, and I was impressed with the dramatic nature of her illness and the idea that diseases could alter vasomotion in such a striking fashion.     

Sedation improves early outcome in severely septic Sprague Dawley rats

Introduction  

Sepsis, a systemic inflammatory response to infective etiologies, has a high mortality rate that is linked both to excess cytokine activity and apoptosis of critical immune cells. Dexmedetomidine has recently been shown to improve outcome in a septic cohort of patients when compared to patients randomized to a benzodiazepine-based sedative regimen. We sought to compare the effects of dexmedetomidine and midazolam, at equi-sedative doses, on inflammation and apoptosis in an animal model of severe sepsis.