细胞穿透肽PEP-1介导血红素加氧酶-1对大鼠离体心脏缺血再灌注损伤的影响

目的 探讨细胞穿透肽PEP-1介导血红素加氧酶-1(HO-1)对大鼠离体心脏缺血再灌注损伤的影响.方法 雄性SD大鼠,体重220～280g,制备Langendorff离体心脏灌注模型,选取模型制备成功的离体心脏18个,随机分为3组(n=6):假手术组(S组)、缺血再灌注组(IR组)和PEP-1/HO-1处理+缺血再灌注组(HO-1组).IR组K-H液平衡灌注30 min后,采用停灌40 min再灌注50 min的方法制备缺血再灌注模型.HO-1组在停灌前用含50 μmol/L融合蛋白PEP-1/HO-1的K-H液平衡灌注15 min,S组采用K-H液持续灌注120 min.再灌注50 min时,收集冠脉流出液,测定肌酸激酶(CK)和乳酸脱氢酶(LDH)的活性;取心肌组织,采用Western blot法测定HO-1蛋白表达水平,采用硫代巴比妥酸比色法测定MDA含量,黄嘌呤氧化酶法测定SOD活性.结果 HO-1组心肌组织HO-1蛋白表达水平较IR组升高(P＜0.01).与S组比较,IR组和HO-1组冠脉流出液CK和LDH活性及心肌组织MDA含量升高,心肌组织SOD活性降低(P＜0.01);与IR组比较,HO-1组冠脉流出液CK和LDH活性及心肌组织MDA含量降低,心肌组织SOD活性升高(P＜0.01).结论细胞穿透肽PEP-1可将HO-1蛋白成功导入心肌组织,并减轻大鼠心肌缺血再灌注损伤.     

不同浓度硝酸甘油对大鼠离体心脏缺血再灌注损伤的影响

目的 探讨不同浓度硝酸甘油对大鼠离体心脏缺血再灌注损伤的影响.方法 健康成年雌性SD大鼠,体重220～330 g,周龄7周,建立Langendorff离体心脏灌注模型,取模型制备成功的心脏30个,随机分为3组(n=10):缺血再灌注组(IR组)K-H液灌注15 min,停灌20 min,再灌注60 min;低浓度硝酸甘油组(LN组)采用含有2.5 μg/L硝酸甘油的K-H液灌注15 min,停灌20 min,再灌注60 min;高浓度硝酸甘油组(HN组)采用含有25μg/L硝酸甘油的K-H液灌注15 min,停灌20 min,再灌注60 min.于再灌注10、20、30、40、50、60 min时记录心率(HR)、冠状动脉流量(CF)、左心室舒张末压(LVEDP)、左心室发展压(LVDP)、左心室内压最大上升速率(+dp/dtmax)和左心室内压最大下降速率(-dp/dt_(max)).于平衡灌注末、再灌注5、30和60 min时收集冠状动脉流出液1.5 ml,测定乳酸脱氢酶(LDH)和肌酸激酶(CK)的活性;于再灌注60 min时取心脏,测定心肌梗死面积,计数心肌凋亡细胞.结果 与IR组比较,LN组HR、CF、LVDP,+dp/dt_(max)和-dp/dt_(max)升高,LVEDP、CK活性、LDH活性、心肌梗死面积和细胞凋亡率降低(P<0.05),HN组HR、CF、LVDP、+dp/dt_(max)和-dp/dt_(max)降低,LVEDP、CK活性、LDH活性、心肌梗死面积和细胞凋亡率升高(P<0.05).与LN组比较,HN组HR、CF、LVDP、+dp/dt_(max)和-dp/dt_(max)降低,LVEDP、CK活性、LDH活性、心肌梗死面积和细胞凋亡率升高(P<0.05).结论 低浓度硝酸甘油(2.5μg/L)可减轻大鼠离体心脏缺血再灌注损伤,而高浓度硝酸甘油(25 μg/L)则可加重心脏缺血再灌注损伤.     

芬太尼后处理、肢体远隔缺血后处理和缺血后处理对大鼠心肌缺血/再灌注初期室性心律失常的影响

目的 对比观察芬太尼后处理、远隔缺血后处理和缺血后处理3种干预措施抑制大鼠心肌缺血/再灌注初期室性心律失常作用的差别.方法 将73只成年雄性SD大鼠(体重250 g～350 g)麻醉后按随机数字表法随机分为9组:空白对照组(S组,n=5);对照组(C组,n=7);芬太尼后处理组(F组,n=9);肢体远隔缺血后处理组(R组,n=9);缺血后处理组(P组,n=8);联合应用芬太尼后处理和肢体远隔缺血后处理组(F-R组,n=9);联合应用芬太尼后处理和缺血后处理组(F-P组,n=8);联合应用肢体远隔缺血后处理和缺血后处理组(R-P组,n=9);联合应用芬太尼后处理、肢体远隔缺血后处理和缺血后处理组(F-R-P组,n=9).所有大鼠开胸后采用丝线套扎其冠状动脉左前降支(left anterior descending coronary artery,LAD)做成活结.除S组之外,所有大鼠接受局部心肌缺血30 min和再灌注60 min的处理.C组不采用任何干预措施;F组、F-R组、F-P组和F-R-P组在LAD结扎15 min时缓慢静脉注射芬太尼30 μg/kg;R组、F-R组、R-P组和F-R-P组在LAD结扎15 min时结扎大鼠双下肢造成肢体缺血10 min后恢复双下肢血流灌注;P组、F-P组、R-P组和F-R-P组开放实施再灌注的初期连续实施3个循环的开放LAD 20 s/阻断LAD 20 s的缺血后处理.记录缺血期和再灌期前30 min内的心律失常评分(AS评分)以及室性心动过速(ventricular tachycardia,VT)和心室纤颤(ventricular fibrillation,VF)的发生率和持续时间.结果 缺血期VT和VF的发生率、VT或VF的持续时间以及AS评分在C组、F组、R组、P组、F-R组、F-P组、R-P组和F-R-P组无统计学差异.C组、F组、R组、P组、F-R组、F-P组、R-P组和F-R-P组再灌注初期AS评分的中位数分别为4、2、2、1、2、1、1和2.与C组比较,其余各组再灌注初期室性心律失常发生显著减少;再灌注初期的VT持续时间和AS在F组和R组之间无统计学差异,但F-R组再灌注初期的VT持续时间则显著降低.与F组和R组比较,P组、F-R组、F-P组、R-P组和F-R-P组再灌注初期的VT持续时间和室性心律失常评分显著减低. 结论 与芬太尼后处理和远隔缺血后处理比较,缺血后处理可更有效抑制再灌注初期室性心律失常的发生.联合应用芬太尼后处理和远隔缺血后处理后,抑制心肌再灌注初期室性心律失常的作用相对增强.     

丙酮酸乙酯预先给药对大鼠离体心脏缺血再灌注损伤的影响

目的 探讨丙酮酸乙酯预先给药对大鼠离体心脏缺血再灌注损伤的影响.方法 雄性SD大鼠24只,体重250～320 g,3月龄,制备Langendorff主动脉逆行灌注模型.随机分为3组(n=8),对照组(C组):改良的K-H缓冲液持续灌流120 min;缺血再灌注组(IR组)改良的K-H缓冲液平衡灌注30 min后,全心停灌30 min,再灌注60 min;丙酮酸乙酯组(EP组)改良的K-H缓冲液平衡灌注15 min后,再用含2 mmol/L丙酮酸乙酯的改良K-H缓冲液平衡灌注15 min,全心停灌30 min,最后用含2 mmol/L丙酮酸乙酯的改良K-H缓冲液再灌注60 min.记录各组平衡灌注15 min(基础值)、再灌注10、30、60 min的左室收缩峰压(LVSP)、左心室内压上升/下降最大速率(±dp/dtmax )、冠脉流量(CF),再灌注60 min时测定心肌ATP含量、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性及冠状动脉流出液中乳酸脱氢酶(LDH)活性、肌酸激酶(CK)的活性.结果 与C组比较,IR组CF、LVSP、±dp/dtmax、SOD活性、ATP含量降低,MDA含量、CK活性、LDH活性升高(P＜0.05),EP组差异无统计学意义(P＞0.05);与IR组比较,EP组CF、LVSP、±dp/dtmax、SOD活性、ATP含量升高,MDA含量、CK活性、LDH活性降低(P＜0.05).结论 丙酮酸乙酯2 mmol/L预先给药通过提高心肌ATP含量,降低氧化应激反应,可减轻大鼠离体心脏缺血再灌注损伤.     

右美托咪啶预处理对大鼠离体心脏缺血再灌注损伤的影响

目的 评价右美托咪啶预处理对大鼠离体心脏缺血再灌注损伤的影响.方法 健康清洁级雄性Wistar大鼠24只,体重230～ 260 g,制备离体Langendorff心脏灌注模型后,采用随机数字表法,将离体心脏随机分为3组(n=8):缺血再灌注组(I/R组)、右美托咪啶Ⅰ组(DI组)、右美托咪啶Ⅱ组(DⅡ组).各组均先用K-H液平衡灌注10 min后,I/R组用K-H液继续灌注30 min,D I组和DⅡ组分别用含有0.23.、2.30ng/ml右美托咪啶的K-H液继续灌注20 min,再用K-H液冲洗10 min.各组心脏均缺血30 min,K-H液再灌注120 min.于平衡灌注末、再灌注5、30、60和120min时收集冠脉流出液,测定肌酸激酶(CK)和乳酸脱氢酶(LDH)活性.再灌注末取心肌组织,测定SOD活性及MDA含量.结果 与I/R组比较DⅠ组和DⅡ组冠脉流出液CK、LDH活性、心肌组织MDA含量降低,心肌组织SOD活性升高(P＜0.05);与DI组比较,DⅡ组冠脉流出液CK、LDH活性、心肌组织MDA含量降低,心肌组织SOD活性升高(P＜0.05).结论 右美托咪啶预处理可减轻大鼠心肌缺血再灌注损伤,且与浓度有关.     

3-硝基丙酸化学预处理对大鼠离体心脏缺血-再灌注损伤的影响

目的研究3-硝基丙酸(3-NPA)化学预处理对大鼠离体心脏缺血-再灌注损伤的保护作用及其机制。方法16只Wistar大鼠随机分为2组,每组8只。实验组(3-NPA组):腹腔注射3-NPAmg·kg-1预处理24h;对照组(C组):腹腔注射等体积生理盐水。采用Langendorff离体心脏灌流模型,两组行常温缺血30min-再灌注60min模拟心肌缺血-再灌注损伤。观察各组缺血前(基础值)和再灌注后30、60min时心率(HR)、左心室发展压(LVDP)、左心室压力上升和下降最大变化速率(±dp/dtmax),测定再灌注后15min时冠脉流出液肌酸激酶(CK)和乳酸脱氢(LDH)活性,测定再灌注后60min时心肌丙二醛(MDA)含量和超氧化物岐化酶(SOD)活性。结果与C组比较,3-NPA组LVDP、 dp/dtmax再灌注后30、60min、-dp/dtmax再灌注后60min时升高(P<0.01或0.05),HR组间比较差异无统计学意义(P>0.05),灌注后15min时冠脉流出液CK和LDH活性降低,再灌注后60min时心肌SOD活性明显升高,心肌MDA含量降低。结论4mg·kg-13-NPA预处理对大鼠离体心脏缺血-再灌注损伤具有一定的保护作用,其机制可能是减少氧自由基的产生和提高SOD活性。     

咪唑安定预处理对缺血-再灌注离体心脏的保护作用

目的探讨咪唑安定预处理对缺血-再灌注离体心脏的保护作用。方法采用Wistar大鼠离体心脏langendofff灌注模型。实验动物随机分为四组,每组8只：正常对照组（C组）,缺血-再灌注组（I-R组）,缺血预处理组（IPC组）,咪唑安定预处理组（MPC组）。观察咪唑安定预处理对心肌缺血-再灌注后不同时间点冠脉流出液中肌酸激酶（CK）、乳酸脱氢酶（LDH）,心肌组织中超氧化物歧化酶（SOD）、髓过氧化物酶（MPO）、丙二醛（MDA）以及再灌注性心律失常、心功能的变化。结果咪唑安定预处理可以减少心肌缺血-再灌注损伤的心肌冠脉流出液中CK、LDH的含量,提高SOD活性,降低MPO、MDA水平,并且抑制再灌注心律失常的发生,保护心功能。结论咪唑安定预处理对缺血-再灌注离体心脏具有一定的保护作用。     

cAMP-PKA信号转导通路在缺血预处理减轻大鼠离体心脏缺血再灌注损伤中的作用

目的 探讨cAMP-PKA信号转导通路在缺血预处理减轻大鼠离体心脏缺血再灌注损伤中的作用.方法 成年SD大鼠50只,体重300-350g,采用Langendorff装置建立大鼠离体心脏缺血再灌注模型后随机分为5组(n=10):缺血再灌注组(IR组)、缺血预处理组(IPC组)、H89组、脯氨酸二硫氨基甲酸组(PDTC组)和双丁酰环磷酸腺苷组(db-cAMP组).K-H液平衡灌注10 min后,R组K-H液继续灌注30 min后停灌1 h,再灌注30 min;IPC组停灌5 min,再灌注5 min.反复3次,停灌1 h再灌注30 min;PDTC和H89组停灌5 min,分别用含有PDTC 100μmol/L和含有H89 10 μmol/L的K-H液再灌注5 min,反复3次,余同IPC组;db-cAMP组用含db-cAMP 200 μmollL的K-H液灌注30 min,停灌1 h再灌注30 min.于平衡灌注10 min、再灌注10、20和30 min时记录左心室压力最大变化速率(±dp/dtmax)和左心室发展压(LVDP).于平衡灌注10 min和再灌注30 min时记录冠脉流出量(CF);测定冠脉流出液中乳酸脱氢酶(LDH)和磷酸肌酸激酶(CK)活性.于再灌注30 min时取心肌组织,采用EMSA法检测NF-κB-DNA结合活性,采用RT-PCR法检测TNF-α mRNA表达,采用Western blot法检测磷酸化环腺苷酸反应元件结合蛋白(p-CREB)(Serl33)表达.结果 与IR组比较,IPC组和db-cAMP组NF-κB-DNA结合活性和TNF-α-mRNA表达降低,±dp/dt和CF升高,CK和LDH活性降低,WC组、PDTC组和db-cAMP组p-CREB(Ser133)表达升高(P<0.05或0.01);与IPC组比较,H89组和PDTC组NF-κB-DNA结合活性和TNF-αmRNA表达升高,±dp/dt、LVDP和CF降低,CK和LDH活性升高.H89组p-CREB(Serl33)表达降低(P<0.05或0.01).结论 缺血预处理通过激活cAMP-PKA信号转导通路抑制NF-κB-DNA结合活性,减少炎性因子的基因转录.从而减轻大鼠离体心脏缺血再灌注损伤.     

大鼠血红素加氧酶-1基因转染对大鼠离体心肌缺血再灌注心肌细胞凋亡的影响

目的 观察重组腺相关病毒介导大鼠血红素加氧酶-1基因转染对大鼠离体心肌缺血再灌注心肌细胞凋亡的影响.方法 雄性SD大鼠30只随机分成3组,对照组(C组,n=6),缺血再灌注组(I/R组,n=12),腺相关病毒介导血红索加氧酶-1基因组(A-r组,n=12).基因转染3个月后,建立大鼠离体心脏Langendorff灌流模型,C组持续灌注100 min,其他各组均平衡15 rain,停灌40min与再灌注45 min,记录冠脉流量(CF),测定冠脉流出液肌酸激酶(CK)活性,测定再灌注后45 min时的心肌心肌组织超氧化物岐化酶(SOD)活性活性及丙二醛(MDA)含量,同时取每组大鼠心肌检测梗死面积、心肌细胞凋亡率以及心肌组织bax、bcl-2蛋白表达量.结果 离体心肌Langendorff灌注后,与I/R组比较,A-r组在复灌后冠脉流出液CK活性降低(P＜0.01),复灌后45min后心肌MDA含量降低(P＜0.01),SOD活性增高(P＜0.01),梗死面积较小(P＜0.01),心肌组织bax表达量、心肌细胞凋亡率均显著下降,心肌组织bel-2表达量明显增加(P＜0.01).结论 重组腺相关病毒血红素加氧酶1基因转染心肌后,可抑制离体缺血再灌注心肌细胞凋亡和增强心肌抗氧化能力,对大鼠离体心肌缺血再灌注损伤有显著保护作用.     

不同剂量丙泊酚预处理对大鼠离体心脏缺血-再灌注损伤的保护作用

目的观察丙泊酚预处理对大鼠离体心脏缺血-再灌注的量效关系。方法建立大鼠离体心脏Langendorff灌流模型,随机分为六组(n=8):缺血-再灌注组(A组)行平衡35min、停灌30min与再灌注120min;丙泊酚预处理组(B、C、D、E组)与脂肪乳预处理组(F组)在平衡15min后依次以12·5、25、50、100μmol/L丙泊酚及脂肪乳预处理10min,冲洗10min,停灌、复灌与A组相同。记录各组心率、机械功能及冠脉流量变化,并对再灌注期间的心律失常进行评分。结果(1)与平衡期比,再灌注后各组心率、机械功能及冠脉流量均显著下降(P<0·01)。与A组比,C、D、E组不同程度减轻上述变化,且D组最显著(P<0·05,P<0·01)。(2)D、E组心律失常评分优于A组。结论丙泊酚预处理改善离体大鼠心脏缺血-再灌注后心脏机械功能与冠脉受损及再灌性心律失常的发生,该作用与其溶剂脂肪乳无关。     

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.     

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.     

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.     

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.     

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.     

Immunomodulation in Transplantation with Photopheresis

Abstract: Photopheresis is a technique in which peripheral blood mononuclear cells, in the presence of a photoacti-vatable compound, are exposed extracorporeally to ultraviolet A light and reinfused, inducing a host autoregula-tory immune response. Experimental work and ongoing clinical studies are helping to define the role of this novel, safe, and non-toxic immunomodulating technology in the field of transplantation.