H2O2氧化应激诱导兔椎间盘髓核细胞衰老的研究

目的:研究H2O2不同浓度对兔椎间盘髓核细胞形态、活力、增值、周期等的影响.方法:新西兰大白兔(2～3 kg,雌)10只,无菌条件下酶消化法分离髓核细胞.含15％FBS的DMEM/F12(1:1)培养液培养,细胞90％融合后传第1代.按照H2O2不同浓度(0μmol/L、130 μmol/L、216 μmol/L、360 μmol/L、600 μmol/L、1 000 μmol/L)分组,0 μmol/L H2O2为空白对照组.在细胞对数生长期,不同浓度H2O2处理1h后原培养液继续培养48 h,通过检测,分析比较各组髓核细胞与空白对照组间形态、活力、增值、周期的差异性.结果:与空白对照组比较,当H2O2浓度为130 μmol/L、216 μmol/L时,髓核细胞生物学特性未见显著性改变(P＞0.05);当H2O2浓度为360 μmol/L、600 μmol/L、1 000 μmol/L时,髓核细胞出现衰老改变:细胞质减少并出现空泡、增值减慢、衰老相关-β-半乳糖苷酶蓝染率增加、细胞周期阻滞于G1期而进入S期减少(P＜0.05).随着H2O2浓度的增高,衰老程度不断升高.结论:一定浓度的H2O2能够导致髓核细胞提前衰老,引起髓核细胞生物学特性的改变.     

白花丹素体外诱导前列腺癌PC-3细胞凋亡的研究

目的 探讨白花丹素对前列腺癌PC-3细胞增殖、凋亡的作用及其和RelA(p65)表达的关系.方法 应用不同浓度梯度的白花丹素(1、5、1O、15、20 μmol/L)共同培养PC-3细胞24、48 h,噻唑蓝(MTT)比色法检测PC-3细胞增殖活力,双染流式细胞仪检测凋亡细胞,透射电镜观察超微病理变化,计算药物半数抑制浓度(IC50).逆转录-聚合酶链反应(RT-PCR)法扩增检测RelA(p65).结果 24 h组在10～20 μmol/L,48 h组在5～20 μmol/L时均出现生长抑制,IC50分别为12.88、3.71 μmol/L.双染流式细胞仪检测显示PC-3随作用浓度的上升凋亡率增加并呈现浓度依赖关系.透射电镜观察作用后PC-3呈现典型凋亡表现.RT-PCR结果提示其细胞凋亡率同Rel A(p65)表达呈负相关.结论 白花丹素体外实验可能通过抑制Rel A(p65)表达诱导PC-3的凋亡.     

姜黄素保护大鼠肾小管上皮细胞对抗氧化应激引起的损伤作用

目的 探讨姜黄素对氧化应激诱导大鼠近端肾小管上皮细胞 (NRK-52E) 损伤作用的影响。 方法 用不同浓度的H2O2处理NRK-52E细胞,建立氧化应激损伤NRK-52E的实验模型。应用Hoechst 33258染色法观察凋亡细胞的形态学改变;PI染色流式细胞仪检测细胞凋亡率;Western印迹法检测Bcl-2蛋白的表达。 结果 H2O2在100~500 μmol/L浓度范围内处理NRK-52E细胞24 h,呈浓度依赖性地增加细胞的凋亡率;500 μmol/L H2O2能显著抑制NRK-52E细胞Bcl-2的表达（P < 0.05）。20 μmol/L和40 μmol/L姜黄素能显著阻断H2O2对NRK-52E细胞的致凋亡作用[（32.9±8.1）%、（22.23±9.3）%比（72.7±10.5）%,均P < 0.05],并能显著拮抗H2O2对Bcl-2蛋白表达的下调作用（P < 0.05）。40 μmol/L姜黄素本身也能上调Bcl-2蛋白的表达（P < 0.05）。 结论 姜黄素能保护NRK-52E细胞对抗氧化应激引起的细胞凋亡,此肾小管上皮细胞保护作用可能与其抑制H2O2对Bcl-2蛋白表达的下调作用有关。     

动脉粥样硬化组织中环氧化酶-2的表达以及选择性环氧化酶-2抑制剂塞来昔布对人血管平滑肌细胞增殖与凋亡的作用

目的 观察环氧化酶-2(COX-2)在动脉粥样硬化组织中的表达以及选择性COX-2抑制剂塞来昔布对体外培养的人血管平滑肌细胞(VSMCs)在细胞增殖和凋亡中的作用.方法 对22例动脉粥样硬化组织切片进行COX-2免疫组织化学染色;对体外培养的原代人VSMCs以不同浓度的塞来昔布处理24 h,以噻唑蓝(MTT)细胞增殖及细胞毒性检测法检测细胞增殖,以流式细胞仪检测细胞早期凋亡.结果 免疫组织化学染色阳性表达率为95％,且在血管内膜、中膜和外膜均有阳性细胞存在;体外培养的人VSMCs中加入塞来昔布可明显抑制COX-2的表达;浓度为0、10、20、40、80 μmol/L的塞来昔布作用于VSMCs 24 h后,以MTF法检测细胞存活率分别为100.00％、90.06％、81.38％、75.41％、68.90％;流式细胞仪检测细胞早期凋亡率分别为0.02％、0.62％、0.92％、1.17％、1.63％.结论 COX-2大量表达于动脉粥样硬化组织中,特别表达于炎性巨细胞以及中层VSMCs中,塞来昔布可抑制体外培养的人VSMCs中COX-2的表达,从而抑制其增殖并诱导其凋亡,两者均呈剂量依赖性.     

冬凌草甲素诱导胃癌SGC-7901细胞凋亡及机制

目的 探讨冬凌草甲素体外诱导胃癌SGC-7901细胞凋亡和细胞周期阻滞的作用及其机制.方法 10～80 μmol/L冬凌草甲素分别处理SGC-7901细胞后,CCK8法检测冬凌草甲素体外对SGC-7901细胞抑制生长的作用;用流式细胞仪分别观察冬凌草甲素诱导凋亡及细胞周期阻滞.Western blot测定凋亡相关蛋白的表达.结果 冬凌草甲素对SGC-7901细胞有明显的生长抑制作用,并随着药物浓度的增加(10～80 μmol/L)而逐渐增强,呈浓度、时间依赖关系.此外,流式细胞术检测发现,冬凌草甲素浓度为0、10、40、60、80 μmol/L,作用24 h后,G_2/M期细胞数分别是(9.90±1.17)%、(9.94±0.27)%、(11.76±0.16)%、(15.64±1.48)%和(22.59±1.01)%;而S期细胞比例分别为(31.79±1.03)%、(30.90±0.47)%、(29.25±0.80)%、(21.46±1.61)%、(18.81±0.61)%,冬凌草甲素能够使得SGC-7901细胞周期呈剂量依赖性阻滞于G_2/M期;冬凌草甲素浓度为80 μmol/L,作用12、24 h后,凋亡率分别为(12.78±1.54)%、(20.62±2.39)%,明显高于对照组的(9.92±0.56)%,其能使SGC-7901细胞发生凋亡.随着冬凌草甲素作用时间延长,SGC-7901细胞的bel-2蛋白表达逐渐减弱,前体Caapase-3被激活.结论 冬凌草甲素能够诱导SGC-7901细胞产生凋亡,并使细胞周期阻滞在G_2/M期.其凋亡机制可能与下调bcl-2蛋白表达及Caspase-3的激活相关.     

鱼藤素对胃癌细胞MKN-45增殖及凋亡的影响

目的:研究鱼藤素对胃癌细胞增殖及凋亡的影响。方法:利用CCK8检测不同浓度(0、1、10和25μmol/L)鱼藤素作用于胃癌细胞MKN-45 24、48、72和96 h后对其增殖的影响;AnnexinⅤ-FITC/PI检测细胞凋亡;流式细胞仪检测细胞周期;利用倒置相差显微镜观察鱼藤素作用后细胞形态的变化;DAPI及Hoechst染色观察细胞核变化。结果:1μmol/L鱼藤素作用于MKN-45细胞24 h后抑制率为(28.82±0.002)%。随着鱼藤素浓度(10、25μmol/L)增加,作用时间(48、72、96 h)延长,其抑制作用增加,表明其抑制作用呈时间-剂量依赖关系。不同浓度(1、10和25μmol/L)鱼藤素作用于细胞48 h后,早期凋亡率、晚期凋亡率和总凋亡率显示鱼藤素显著促进细胞凋亡。细胞周期检测发现,与对照组比较,1μmol/L鱼藤素作用于细胞48 h后,S期细胞比例升高,G_0/G_1期及G_2/M期细胞比例下降;10μmol/L鱼藤素作用于细胞48 h后,G_2/M期细胞比例升高,G_0/G_1期细胞比例下降(P     

兔血管平滑肌细胞活性氧的生成途径

目的探讨兔血管平滑肌细胞(VSMC)生成活性氧的途径。方法兔VSMC原代培养,噻唑蓝(MTT)法检测不同浓度过氧化氢(H2O2)对VSMC活力的影响;100μmol／L H2O2作用后不同时段,流式细胞仪检测VSMC细胞内超氧阴离子(·O2-)生成;逆转录-聚合酶链反应(RT- PCR)检测VSMC NADPH氧化酶各亚基mRNA表达。结果随H2O2浓度增加,VSMC细胞活力逐渐下降,浓度≥30μmol／L时,各时段吸光度值即有显著降低(P<0．05)。100μmol／L H2O2作用后,(1)VSMC细胞内·O2-生成,其作用在24 h达峰值(DHE阳性细胞百分率24．01％);(2)VSMC p22phox mRNA的表达增加,并在1 h达峰值(为0 h的2倍),gp91phox和nox1 mRNA的表达下降,尤其nox1,在1 h达最低值(为0 h的15％)。结论一定浓度的外源性H2O2可促进VSMC生成·O2-,NADPH氧化酶参与这一细胞效应。     

容量敏感外向整流性氯通道参与氧化应激介导的系膜细胞凋亡

目的 探讨容量敏感外向整流性(VSOR)氯通道在H2O2介导系膜细胞凋亡中的作用和可能的机制。 方法 全细胞膜片钳技术用于检测VSOR氯电流。细胞凋亡通过吖啶橙/溴化乙锭荧光染色、电子显微镜、TUNEL染色和半胱氨酸天冬氨酸蛋白酶(caspase)-3活性确定。 结果 150 μmol/L H2O2激活系膜细胞VSOR氯电流，H2O2激活的氯电流具有典型的VSOR氯电流电生理特性，包括：外向整流性、电压依赖性失活。对细胞外高渗透压敏感及被VSOR氯通道阻断剂抑制。VSOR氯通道阻断剂DIDS(100 μmol/L)，NPPB(10 μmol/L)和尼氟灭酸(10 μmol/L)明显抑制H2O2介导的系膜细胞凋亡。150 μmol/L H2O2处理2 h内，细胞容量明显下降，但这种细胞容量下降被100 μmol/L DIDS，10 μmol/L NPPB和10 μmol/L尼氟灭酸抑制。结论 VSOR氯通道参与H2O2介导的系膜细胞凋亡，其机制与介导凋亡性容量下降有关。     

芹黄素对前列腺癌细胞生长和凋亡的影响

目的 :探讨芹黄素 (Apigenin)对前列腺癌 (PCa)细胞的体外杀伤效应 ,及其对前列腺癌 (PCa)细胞周期与凋亡的影响。方法 :以锥虫蓝拒染法进行细胞计数并计算芹黄素组与对照组细胞数比率 ,MTT法检测细胞生长抑制率 ,并采用流式细胞术 (FCM )检测细胞凋亡和细胞周期变化。结果 :芹黄素 0 .1μmol/L组细胞数未见明显改变 ,其余各组随浓度和时间的推移 ,细胞数比率逐渐下降 ,呈时间和剂量依赖关系 (P <0 .0 5～ 0 .0 1) ;这种作用在 1、10 μmol/L组可逆转 ,而在 10 0 μmol/L组不可逆转。MTT检测 1、10、10 0 μmol/L三个浓度组作用至2 4h后 ,细胞生长抑制率分别为 (5 .15± 0 .2 1) %、(10 .6 9± 1.80 ) %和 (18.16± 2 .34) % ;作用至 96h后 ,生长抑制率递增至 (2 4 .0 4± 3.34) % ,(36 .89± 2 .74 ) %和 (5 4 .18± 2 .6 0 ) %。芹黄素可使PC 3m细胞发生G0 /G1期细胞周期阻滞 ,高浓度组尤为明显 ,并在 10 0 μmol/L组诱导一定比例 (16 .19% )的细胞凋亡。结论 :芹黄素可能通过阻滞细胞周期和诱导细胞凋亡实现对PCa细胞的生长抑制作用。这为深入研究饮食结构与PCa的预防和治疗提供初步的实验依据。     

普鲁士蓝纳米粒对过氧化氢诱导脂肪间充质干细胞凋亡的影响

目的探究普鲁士蓝纳米粒(PBNPs)对过氧化氢(H2O2)诱导脂肪间充质干细胞(ADSCs)凋亡的影响及其相关机制。方法水热合成法制备PBNPs, 电镜、傅里叶变换红外光谱等表征PBNPs合成;流式鉴定ADSCs表面标志物CD29、CD90、CD44、CD73、CD45、CD34;噻唑蓝(MTT)法检测H2O2、PBNPs细胞毒性;细胞分为Control组、H2O2组(200 μmol/L H2O2处理24 h)、L-PBNPs组(10 μg/ml PBNPs预处理12 h后, 200 μmol/L H2O2处理24 h)、H-PBNPs组(20 μg/ml PBNPs预处理12 h后, 200 μmol/L H2O2处理24 h);活性氧探针检测ADSCs的活性氧水平;流式细胞仪分析ADSCs的凋亡水平;蛋白质印迹法检测凋亡相关蛋白表达水平;两组间比较采用t检验, 多组间比较采用单因素方差分析(One-way ANOVA)。结果 PBNPs为正立方体, 表面Fe、C、N等元素均匀分布;ADSCs CD29、CD90、CD44、CD73阳性, CD45、CD34阴性;L-PBNPs组和...     

Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background : We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI₂) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods : In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGFlα (stabile metabolite of PGI₂), TXB₂ (stabile metabolite of thromboxane A₂) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results : Following MT, arterial hypotension occurred along with a substantial PGI₂ release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF_1α (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same point in time plasma concentrations of TXB² (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41 ± (18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P = 0.001) were significantly higher in placebo-treated patients. Conclusion : Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI₂ release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A₂, presumably contributing to hemodynamic stability within 30 min after MT.     

A Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

Microspheres Based Detoxification System: A New Method in Convective Blood Purification

Abstract: A variety of protein-bound or hydrophobic substances, accumulating as a result of pathologic conditions such as exogenous or endogenous intoxications, are removed poorly by conventional detoxification methods because of low accessibility (hemodialysis), insufficient adsorption capabilities (hemosorption), low efficiency (peritoneal dialysis), or economic limitations (high-volume plasmapheresis). Combining advantages of existing methods with microspheric technology, a module-based system was designed. Major operating parameters of the latter can be modified to allow for adjustment to individual clinical situations. An extracorporeal blood circuit including a plasmafilter is combined with a secondary high-velocity plasma circuit driven by a centrifugal pump. Different microspheric adsorbers can be combined in one circuit or applied in sequence. Thus, a prolonged treatment can be tailored using specially designed selective adsorber materials. Comparing this system with existing methods (high-flux hemodialysis, molecular adsorbent recycling system), results from our in vitro studies and animal experiments demonstrate the superior efficiency of substance removal.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

Bariatric Surgery in Some "Central and East-European (former Eastern bloc)"Countries - Current Status and Prediction for the Next Millennium

Background: Obesity is increasing globallly, including in the formerly "Eastern Bloc" countries. Methods: A survey was made of obesity and bariatric surgery. Results: In the 8 East and Central European countries studied, with total population 300 million, roughly 43% of the population was overweight (BMI 25-30), 23% obese (BMI > 30), with about 15 million people morbidly obese (BMI > 40). From 0-10 morbidly obese individuals/100,000/year undergo bariatric surgery. Conclusion: Most countries were found to provide inadequate treatment for obesity.The majority of the morbidly obese are not treated effectively. However, health-care awareness of obesity and bariatric surgeons are slowly increasing.     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

Influence of dopexamine hydrochloride on haemodynamics and regulators of circulation in patients undergoing major abdominal surgery

Background: Catecholaminergic support is often used to improve haemodynamics in patients undergoing major abdominal surgery. Dopexamine is a synthetic vasoactive catecholamine with beneficial microcirculatory properties. Methods: The influence of perioperative administration of dopexamine on cardiorespiratory data and important regulators of macro- and microcirculation were studied in 30 patients undergoing Whipple pancreaticduodenectomy. The patients received randomized and blinded either 2 μg · kg^?1 · min^?1 of dopexamine (n=15) or placebo (n=15, control group). The infusion was started after induction of anaesthesia and continued until the morning of the first postoperative day. Endothelin-1 (ET-1), vasopressin, atrial natriuretic peptide (ANP), and catecholamine plasma levels were measured from arterial blood samples. Measurements were carried out after induction of anaesthesia, 2 h after onset of surgery, at the end of surgery, 2 h after surgery, and on the morning of the first postoperative day. Results: Cardiac index (CI) increased significantly in the dopexamine group (from 2.61±0.41 to 4.57±0.78 1 · min^?1 · m^?2) and remained elevated until the morning of the first postoperative day. Oxygen delivery index (DO₂I) and oxygen consumption index (VO₂I) were also significantly increased in the dopexamine group (DO₂I: from 416±91 to 717±110 ml/m² · m²; VO₂I: from 98±25 to 157±22 ml/m² · m²), being significantly higher than in the control group. pHi remained stable only in the dopexamine patients, indicating adequate splanchnic perfusion. Vasopressive regulators of circulation increased significantly only in the untreated control patients (vasopressin: from 4.37±1.1 to 35.9±12.1 pg/ml; ET-1: from 2.88±0.91 to 6.91±1.20 pg/ml). Conclusion: Patients undergoing major abdominal surgery may profit from prophylactic perioperative administration of dopexamine hydrochloride in the form of improved haemodynamics and oxygenation as well as beneficial influence on important regulators of organ blood flow.     

Synergistic interaction between the effects of propofol and midazolam with fentanyl on phrenic nerve activity in rabbits

Background: It has been shown that the depressive effects of both propofol and midazolam on consciousness are synergistic with opioids, but the nature of their interactions on other physiological systems, e. g. respiration, has not been fully investigated. The present study examined the effect of propofol and midazolam alone and in combination with fentanyl on phrenic nerve activity (PNA) and whether such interactions are additive or synergistic. Methods: PNA was recorded in 27 anaesthetised and artificially ventilated rabbits. In three groups, propofol, fentanyl and midazolam were administered intravenously in incremental doses to construct dose-response curves for the depressant effects of each one on PNA. In another two groups, the effect of pretreatment with either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. on the effects of propofol and fentanyl respectively on PNA were studied. Results: Propofol and fentanyl caused a dose-dependent depression of PNA with complete abolition at the highest total doses of 16 mg · kg^?1 i. v. and 32 μg · kg^?1 i. v., respectively. In contrast, midazolam in incremental doses to a total of 0.8 mg · kg^?1 reduced mean PNA by 63%, but approximately 12% of PNA remained at a total dose as high as 6.4 mg · kg^?1. The mean ED₅₀s, calculated from dose-response curves, were 5.4 mg · kg^?1, 3.9 μg · kg^?1 and 0.4 mg · kg^?1 for propofol, fentanyl and midazolam, respectively. Initial doses of either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. acted synergistically with subsequent doses of either propofol or fentanyl to abolish PNA at total doses of 8 mg · kg^?1 and 8 μg · kg^?1, respectively. Conclusion: Fentanyl has a synergistic interaction with both propofol and midazolam on PNA and hence potentially on respiration.