人源类溶菌酶蛋白4的多克隆抗体制备及其表达分析

目的:以原核表达的人源类溶菌酶蛋白4(LYZL4)为免疫原制备多克隆抗体,检测LYZL4在睾丸组织中的定位,为阐明其生理功能提供依据。方法:将LYZL4编码基因克隆于原核表达载体pET32a,IPTG诱导重组LYZL4(r LYZL4)表达。分别使用Ni-NTA树脂和甲壳素亲和层析纯化rLYZL4,采用双层琼脂平板扩散法检测杀菌活性。以Ni-NTA树脂纯化产物为免疫原制备兔抗rLYZL4多克隆抗体,通过ELISA测定抗体效价,Western印迹检测抗体特异性后,检测LYZL4蛋白在人体各组织的分布及其在精子和精浆中存在情况,免疫组化确认LYZL4在人睾丸组织中的定位。结果:原核表达系统可有效表达rLYZL4,其对溶壁微球菌及大肠杆菌无杀灭活性。制备的兔抗rLYZL4多克隆抗体具有很高的效价和特异性,在睾丸、附睾及人精子蛋白提取物中可检测到LYZL4存在,在生精小管中,LYZL4定位于圆形精子细胞及长形精子细胞的顶体上。结论:本研究成功以原核表达的rLYZL4制备了该蛋白的多克隆抗体,确认LYZL4在睾丸和附睾有表达,并定位于精子顶体上,提示其可能与顶体结构或功能相关。     

肝癌相关蛋白FAM172A2的克隆表达及多克隆抗体制备

目的 构建肝癌相关蛋白FAM172A2的原核表达载体,诱导融合蛋白的表达,并对其进行纯化;制备兔抗FAM172A2蛋白多克隆抗体并进行鉴定.方法 应用逆转录-聚合酶链反应(RT-PCR)技术,以HepG2细胞总RNA为模板,扩增FAM172A2目的基因片段1113bp,构建原核表达载体,Western blot分析证实融合蛋白表达的特异性.诱导其大量表达后纯化、复性并制备多克隆抗体,Western blot及酶联免疫吸附试验(ELISA)检测特异性及其效价.结果 扩增获得FAM172A2基因片段,成功诱导FAM172A2融合蛋白表达并制备其多克隆抗体.ELISA检测证实其效价＞1∶160000,且特异性良好.结论 利用大肠埃希菌BL21( DE3)能够成功表达FAM172A2蛋白,获得高特异性、高效价兔抗FAM172A2蛋白的多克隆抗体.     

人髓样细胞触发受体-1原核表达载体的构建和表达及多克隆抗体的制备

目的 构建人髓样细胞触发受体-1(TREM-1)原核表达载体使其表达并制备多克隆抗体。方法 采用特异性引物扩增人TREM-1胞外段cDNA,经酶切、连接、构建到原核表达载体pET28a(+),将构建的重组表达质粒转化入E.coli BL21( DE3)菌株,采用IPTG诱导表达、Ni-NTA 柱亲和层析纯化目的蛋白、SDS-PAGE分析蛋白纯度,将纯化的目的蛋白免疫家兔制备多克隆抗体,并对其进行纯化及鉴定。结果 序列测定证实构建的重组表达载体pET28a(+)-TREM-1含有人TREM-1编码序列,其序列分析与Genbank中公布序列对比一致,质粒在E.coli中诱导表达相对分子质量(Mr)为21.80 kDa的目的蛋白,SDS-PAGE分析表明纯化后的目的蛋白达到电泳纯,双向琼脂扩散法检测抗体效价为1:16,ELISA法检测抗体效价为1:25 600,Western blot分析显示抗体能特性结合人TREM-1重组蛋白。结论 成功构建高表达重组人TREM-1蛋白的原核表达载体及制备高效价兔抗人TREM-1多克隆抗体。     

人胃动素受体基因表达载体的构建

目的 构建人胃动素受体基因的原核表达载体。方法 通过巢式PCR扩增人基因组DNA，获得人胃动素受体基因的658bp的靶片段，将其粘端克隆，然后应用限制性酶切、半巢式PCR扩增及测序鉴定。结果 成功克隆了人胃动素受体基因表达片段，测序证实读框正确。结论 人胃动素受体表达片段获得成功克隆。     

SLC35 F2抗体制备与非小细胞肺癌组织中SLC35 F2蛋白表达检测

目的 制备SLC35F2多肽抗体,鉴定其性能,检测其对应蛋白在非小细胞肺癌(NSCLC)组织中的表达.方法 通过蛋白质序列分析,选4段氨基酸序列合成多肽,混合免疫家兔,制备抗SLC35F2多肽抗体,经纯化、效价检测、特异性鉴定后,将抗体用于NSCLC标本免疫组织化学染色.结果 获得兔抗人SLC35F2多肽抗体,效价1:10<"5,Western blot可特异识别41 KD的SLC35F2蛋白,免疫组织化学示细胞胞质特异性染色.129例NSCLC的组织微阵列免疫组织化学染色显示,SLC35F2蛋白表达在90.7%(117/129)肺癌标本为++到+++;而仅在17.1%(22/129)癌旁正常肺组织为++,其余为-或+;SLC35F2蛋白表达在NSCLC组织中高于癌旁正常肺组织(P<0.01);NSCLC病理分期与SLC35F2的升高表达存在低度相关(r=0.175).结论 用多肽免疫家兔制备抗SLC35F2抗体具有较高的效价和特异性,SLC35F2在NSCLC中表达高于癌旁正常组织.     

SFRP2基因重组腺病毒载体的构建与鉴定

目的:成功构建携带SFRP2基因的腺病毒载体。方法:从pGBKT-SFRP2质粒中扩增SFRP2基因,将SFRP2基因亚克隆至质粒穿梭载体pAd-Track-CMV。用脂质体转染法将重组腺病毒pAd-Track-PPARγ2-CMV和pAdEasy-1共转染293细胞,成功构建的重组腺病毒Ad-SFRP2,确定转染效率。原代培养增生性瘢痕成纤维细胞,利用Ad-SFRP2感染该细胞。通过RT-PCR和Western Blot分别检测感染后人瘢痕成纤维细胞及对照组细胞中SFRP2基因mRNA和蛋白表达水平。结果:RT-PCR检测结果显示腺病毒Ad-SFRP2的PCR产物约为904bp,SFRP2 mRNA表达水平明显增高;用抗SFRP2多克隆抗体进行Westernblot检测为阳性,感染的重组腺病毒载体在人瘢痕成纤维细胞中SFRP2蛋白有较高的稳定表达。结论:成功构建含有人SFRP2基因的重组腺病毒Ad-SFRP2;它可有效提高人增生性瘢痕成纤维细胞中SFRP2基因的表达水平。     

人内皮高表达脂多糖相关因子1多克隆抗体的制备

目的 制备人内皮高表达脂多糖相关因子 1(EOLA1)多克隆抗体,检测EOLA1在人脐静脉内皮细胞(HUVEG)中的表达.方法 复性成功表达EOLA1的蛋白样品(样品1和2),二辛丁酸法检测2种蛋白样品浓度,应用肽质量指纹图谱(PMF)分析法对2种样品进行验证.采用与理论肽段符合率高的EOLA1蛋白样品免疫4只小鼠,同时取4只未免疫小鼠作对照.采集各小鼠血液分离血清,应用饱和硫酸铵盐析沉淀法纯化EOLA1多克隆抗体,ELISA法分析效价(数据以吸光度值表示).蛋白质印迹法检测EOLA1在HUVEC中的表达.结果 蛋白样品1和2的浓度分别为0.124 16、0.132 15 mg/mL.PMF分析显示,样品1的理论肽段符合率为32%,样品2的理论肽段符合率为24%.选用蛋白样品1免疫小鼠,经检测抗体效价在1∶10 000以上;应用制备的EOLA1多克隆抗体可以检测到EOLA1蛋白在HUVEC中表达.结论 应用EOLA1原核表达蛋白免疫小鼠可以制备EOLA1多克隆抗体,并可用于检测EOLA1蛋白表达.     

人前脑啡肽基因修饰人胚胎肾细胞的构建

目的 构建人前脑啡肽基因(hPPE)修饰的人胚胎肾细胞(HEK293细胞).方法 重组质粒pcDNA3.1(+)/hPPE经限制性内切酶HindⅢ和Not Ⅰ进行双酶切获得hPPE基因,运用基因重组技术将hPPE基因与表达载体同源重组,转染293T细胞进行慢病毒包装、扩增、纯化,测定病毒滴度,再将重组的慢病毒载体转染HEK293细胞.用Western blot法检测hPPE基因在HEK293细胞中的表达.结果 重组慢病毒载体阳性克隆测序结果和基因库的hPPE基因序列完全一致.含有hPPE基因的慢病毒载体,滴度为2.07×108TU/ml.转染慢病毒载体后的HEK293细胞,在荧光显微镜下未见到GFP荧光.转染Ubc-GFP-L.V.空病毒载体的HEK293细胞,可见到较强的荧光.Western blot法检测到经慢病毒载体转染后的HEK293细胞中hPPE基因表达呈阳性.结论 成功构建了hPPE基因修饰的HEK293细胞,使hPPE基因可在HEK293细胞中稳定表达.     

大鼠ETFβ基因过表达对NADPH氧化酶基因表达的影响

目的:构建大鼠ETFβ的重组质粒并检测其在人胚胎肾293T细胞中的表达和对NADPH氧化酶的影响。方法:应用RT-PCR方法从大鼠肾脏组织总RNA中扩增出编码ETFβ的cDNA,克隆至pUM-T载体并测序,然后亚克隆至真核表达载体pcDNA3.1/V5-His,酶切鉴定后测序,测序正确后用磷酸钙共沉淀法瞬时转染HEK293T细胞,使用RT-PCR方法检测空载体组和重组质粒转染组的NADPH氧化酶各亚基mRNA水平的表达变化。结果:(1)测序结果证实PCR扩增得到编码ETFβ的cDNA序列正确;(2)磷酸钙共沉淀法转染HEK293T细胞后,ETFβ融合蛋白成功表达;(3)RT-PCR结果显示重组质粒转染组的NADPH氧化酶5个亚基中的NOX3,NOX4的mRNA表达降低(P<0.05),空载体组和重组质粒转染组之间比较NOX1,NOX2,NOX5的mRNA表达差异无统计学意义。结论:成功构建大鼠ETFβ的重组质粒,该重组质粒可在HEK293T中过表达,并且降低了NADPH氧化酶NOX3,NOX4的mRNA表达水平。     

FAM172A及其异构体重组蛋白对体外培养肝细胞增殖的影响

目的体外克隆人类基因FAM172A,构建其原核表达载体并诱导其重组蛋白的表达,制备兔抗FAM172A重组蛋白的多克隆抗体,观察其在不同细胞系的表达情况。观察FAM172A-1和FAM172A-3蛋白对L02细胞增殖的影响。方法利用反转录聚合酶链反应（RT-PCR）及PCR技术,构建原核表达质粒pET-32a（＋）-FAM172A-1和pET-32a（＋）-FAM172A-3。诱导该基因不同异构体重组蛋白的表达,并通过蛋白质免疫印迹（Western blot）技术进行鉴定。纯化后的重组蛋白FAM172A-1和FAM172A-3与肝细胞L02细胞共孵育,观察不同浓度的重组蛋白对细胞增殖的影响。利用纯化后的FAM172A（异构体3）重组蛋白免疫大耳白兔,获得抗FAM172A-3蛋白的多克隆抗体,利用酶联免疫吸附法（ELISA）以及Western blot技术对获得的多克隆抗体进行效价分析及特异性检测。结果成功扩增获得FAM172A（异构体1、3）的基因片段,测序结果与GenBank已公开的基因序列一致;成功表达FAM172A（异构体1、3）的重组蛋白,经过Western blot鉴定正确;纯化后的重组蛋白FAM172A （异构体1、3）与L02细胞共孵育结果发现,两者对L02细胞在一定浓度范围内均有促进细胞增殖的作用。所制备的兔抗人FAM172A-3重组蛋白的多克隆抗体,ELISA检测显示其效价可达1︰1280000, Western blot检测证实该多克隆抗体的特异性良好;Western blot分析显示,该蛋白在肝脏间质细胞和实质细胞均有一定程度的表达。结论 FAM172A蛋白在肝实质细胞及肝间质细胞均表达,且其重组蛋白可以促进L02细胞增殖,推测该基因可能与肝细胞损伤、肝纤维化以及肝细胞再生等发生机制有关。     

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.     

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.