前列腺特异性膜抗原启动子增强子调控重组质粒的构建及鉴定

目的探讨前列腺特异性膜抗原(PSMA)启动子和增强子调控目的基因表达的前列腺细胞特异性，了解增强子增强转录效率的能力。方法采用PCR方法从前列腺癌细胞DNA中分别扩增PSMA启动子和增强子序列，先后克隆到含有报告基因绿色荧光蛋白(GFP)的质粒载体，脂质体介导基因转染不同癌细胞并观察GFP在不同细胞的表达情况。结果成功构建质粒pEGFP—PS—MAPro和pEGFP-PSMAEP，转染结果显示PSMA表达阳性的LNCaP细胞中存在GFP的有效表达，且pEGFP—PSMAEP的调控转录能力较pEGFP—PSMAPro强20倍。结论PSMA启动子增强子调控GFP表达的重组质粒的构建证明该调控序列具有前列腺细胞特异性，增强子能够明显增强启动子的转录效率，增加了目的基因的表达水平。PSMA启动子和增强子的共调控可以保证基因表达的强度和细胞特异性，为前列腺癌基因靶向性治疗研究提供实验依据。     

肝癌组织特异性蛋白磷酸酶2A催化性C亚基α亚型显性负性突变体表达载体抑制肝癌移植瘤生长的体内研究

目的 构建腺病毒为载体的肝癌组织特异性启动子驱动的蛋白磷酸酶2A催化性C亚基α亚型显性负性突变体(domina negative form of protein phosphatase 2A catalytic subunit α,DN-PP2Acα)表达载体,研究其对肝癌生长的影响.方法 前期研究已构建了甲胎蛋白(alpha-fetoprotein,AFP)基因增强子和磷酸甘油酸激酶(phosphoglycerate kinase,pgk)基因启动子组合形成的肝癌组织特异性AFpg启动子,并将AFpg启动子和DN-PP2Acα编码序列构建成AFpg启动子调控的DN-PP2Acα表达载体.将该载体重组到腺病毒载体中.Western印迹法检测PP2Ac表达水平.MTT法检测细胞生长.用荷瘤裸鼠进行体内研究.结果 AFpg启动子调控的DN-PP2Acα表达载体可特异性地使DN-PP2Acα表达于AFP阳性肝癌细胞HepG2,并抑制细胞及移植瘤的生长,而对AFP阴性肝癌细胞株SK-HEP-1、正常肝细胞株L-02和移植瘤的生长无明显影响.结论 AFpg启动子调控的DN-PP2Acα表达载体能特异性地抑制AFP阳性肝癌细胞的生长,可用于肝癌组织特异性基因治疗.     

肝癌特异性血管抑制疗法的真核表达载体的构建及其表达

目的构建受甲胎蛋白(AFP)增强子和白蛋白(Alb)启动子调控的含有血管抑制素(angiostatin)K5序列的真核表达载体,通过基因转染,将angiostatinK5基因导入肝癌细胞,观察angiostatinK5的表达。方法用RT-PCR法从正常人真核细胞扩增出angiostatinK5基因,将AFP增强子和Alb启动子调控序列定向克隆入真核表达载体pcDNA3.1,并将angiostatinK5cDNA置于上述调控序列之下,从而构建得到重组真核表达载体pcDNA3.1-AFAB-angiostatinK5-His。利用细胞培养、脂质体介导的细胞转染,将angiostatinK5基因导入肝癌细胞。利用SDS-PAGE和Westernblot法检测肝癌细胞中angiostatinK5的表达。结果通过酶切鉴定及DNA测序证实目的真核表达载体pcDNA3.1-AFAB-angiostatinK5-His与预期的结果相同。SDS-PAGE及Westernblot分析证明,angiostatinK5在肝癌细胞中得以表达。结论构建的肝癌特异性重组真核表达载体可增加对AFP阳性肝癌细胞的治疗的特异性,并用于实现对肝癌的特异性血管抑制作用。     

人肝癌特异性 HSV-TK/GCV重组腺病毒相关病毒质粒的构建与研究

目的 构建肝癌特异性HSV—TK／GCV重组腺病毒相关病毒质粒并了解其在细胞内的表达。方法 以腺病毒相关病毒的质粒WAV2作为载体，将TK基因插在甲胎蛋白(AFP)增强子／白蛋白启动子(AFP增强子／ALB启动子)的调控基因的下游，重组成pWAV2／AFP-ALB／HYTK质粒载体。同时构建质粒载体pEGFP-1／AFP—ALB。然后将上述两种不同载体分别转入AFP阳性表达的HepG2细胞株以及阴性表达的7721、SPC和7901细胞株。结果 绿色荧光蛋白只在AFP阳性表达的HepG2细胞株表达，采用PCR技术，以HSV—TK的引物扩增所抽提的总DNA中，只有AFP阳性表达的HepG2细胞株扩增出了710bp的DNA片段。结论 pWAV2／AFP—ALB／HYTK质粒载体在体外实验中具有很好的靶向性。     

肝癌特异性p53基因腺相关病毒载体的构建

目的 构建一种肝癌细胞靶向性的腺相关病毒载体以用于肝癌的促凋亡基因治疗的研究。方法 通过设计含有特定酶切位点的引物,选择地从人基因组中出入甲胎蛋白（α－fe-toprotein,AFP）启动子序列并克隆以真核表达载体pTR－UF5上;再通过平端连接的方法,构建成含甲胎蛋白启动子和人野生型p53基因的重组腺相关病毒（recombinant adeno-associated virus,rAAV）质粒rAAV－AFP－53和绿色荧光蛋白基因GFP（green fluorescence protein）的质粒rAAV－AFP－GFP。结果 成功地构建了以腺相关病毒为载体、受人甲胎蛋白启动子调控表达人野生型p53基因的质粒系统。结论 从理论上说,我们构建的重组腺相关病毒质粒rAAV－AFP－p53,可以特异性地转染到肝癌细胞中从而为肝癌基因治疗提供一种有效手段。     

SM22α启动子慢病毒载体的构建及感染研究

目的 构建以SM22α启动子驱动EGFP表达的慢病毒载体,研究此载体在血管平滑肌细胞(vascular smooth muscle cells,VSMCs)中表达的效率和特异性.方法 从小鼠的基因组中采用PCR扩增SM22α启动子,将目的基因连接至T载体,并进行测序鉴定,将目的基因重组至pGC-FU载体,三质粒系统采用脂质体介导转染293T细胞进行病毒包装,体外感染VSMCs,大鼠动脉内皮细胞,人乳腺癌细胞系SK-BR-3,荧光显微镜观察EGFP的表达情况.结果 PCR扩增得到的SM22α启动子经测序证实正确;成功构建了SM22α启动子驱动EGFP的慢病毒载体LV-SM22α-EGFP,SM22α启动子能调控EGFP在VSMCs中高效表达,感染效率在95%以上,在血管内皮细胞和人乳腺癌细胞系SK-BR-3中不表达,对照慢病毒组EGFP在三种细胞中均表达,在VSMCs的感染效率在30%左右,且表达较低.结论 SM22α启动子能够特异性驱动EGFP在VSMCs中表达,LV-SM22α-EGFP能作为研究血管疾病的良好基因转移载体.     

肝癌基因治疗的靶向性研究进展

目的　介绍目前关于肝癌基因治疗靶向性研究的进展。方法　采用文献回顾的方式对肝癌基因治疗研究中采用的组织特异性载体系统以及细胞特异性基因表达调控系统等相关文献进行了综述。结果　合成的DNA转运系统和经修饰的病毒载体体外转染靶细胞后 ,可获得显著表达。目的基因细胞特异性表达主要是以甲胎蛋白或白蛋白基因的转录调控元件为基础 ,体外实验显示出较强的作用靶向性。其它基因治疗策略也显示了很好的应用前景。结论　寻找更具特异性和普遍性的肝癌抗原是解决基因治疗靶向性的关键。根据疾病和患者的具体情况选择合适的基因转运系统和调控元件是未来基因治疗的方向。     

端粒酶逆转录酶启动子联合CD自杀基因靶向杀伤人肝癌细胞研究

目的 利用肿瘤特异性人端粒酶逆转录酶(hTERT)启动子介导自杀基因CD表达,检测其促进5-FC对肝癌细胞系的杀伤作用.方法 采用聚合酶链反应(PCR)技术获得hTERT基因的启动子片段,将其连至SV40增强子序列后,并克隆到表达荧光素酶基因的报告质粒上,检测hTERT基因启动子在肝癌细胞系Bel-7402和人成纤维细胞HDF中的转录活性,同时将CD自杀基因连至该调控序列后,转染肝癌细胞Bel-7402,通过逆转录(RT)-PCR、噻唑蓝(MTT)比色法检测其作为肝癌基因治疗中肿瘤特异性靶向杀伤载体的可行性.结果 成功构建pGL3-SV40-hTERT载体和SV40-hTERT-CD-GFP质粒载体,转染ST-CD载体后Bel-7402细胞表达CD基因,转染PGL3-SV40-hTERT质粒后Bel-7402细胞中hTERT启动子高表达,相对活性为354%.与未转染组比较,5-Fc对转染SV40-hTERT-CD-GFP质粒载体的肝癌细胞Bel-7402的杀伤效应明显增强(F=27.831,P<0.01).结论 hTERT启动子在肝癌细胞系中具有较强的转录活性,能有效地诱导CD自杀基因的表达.     

靶向肝癌细胞的重组腺相关病毒载体的构建

目的　构建以甲胎蛋白增强子(AFP E)和白蛋白启动子(ALB P)联合转录调控序列(AFPenh+ALBprom, EP)为启动子的重组腺相关病毒基因治疗载体,用于肝细胞肝癌(HCC)的靶向基因治疗研究。方法　用PCR方法扩增EP基因片段,将EP基因片段顺义克隆至重组腺相关病毒载体系统(AAV Helper Free System)中表达质粒 pAAV IRES hrGFP的启动子位点,并替换其原有的巨细胞病毒(CMV)启动子,构建出以 EP为启动子的表达质粒 pAAV IRES hrGFP EP; 再将 pAAV IRES hrGFP EP与 AAV Helper Free System中的控制质粒pAAV RC和辅助质粒 pHelper用脂质体转染法共转染人胚肾细胞(293 细胞),生成以 EP 为启动子的、可用于HCC靶向基因治疗的重组腺相关病毒载体(rAAV EP)。结果　成功构建并包装出以 EP为启动子的重组腺相关病毒载体 rAAV2 EP,病毒滴度达1.2×105/ml。结论　构建的以腺相关病毒为载体、受 AFP E和 ALB P联合转录调控序列驱动的重组腺相关病毒载体 rAAV2 EP,可望能用于HCC靶向基因治疗研究,并为肝脏疾病的靶向基因治疗提供先进载体系统。     

睾丸特异性新基因T490真核荧光表达载体的构建及其表达

目的 构建含有增强型绿色荧光蛋白(EGFP)报告基因的睾丸特异性新基因T490超表达质粒pDT490-EGFP,检测其在Hela细胞中的表达情况.方法 采用RT-PCR的方法从成年Balb/c小鼠睾丸组织中扩增T490基冈,将该基凶连接克降到含有增强型绿色荧光蛋白(EGFP)报告基因的真核表达载体pEGFP-N1上,再将T490和EGFP融合基因酶切下来,克隆到pcDNA3.1(-)真核超表达载体上,以构建重组质粒pDT490EGFP.将该重组质粒通过阳性脂质体Lipofectamine 2000导入Hela细胞系中,在荧光显微镜F观察转染24h后融合基因的超表达情况,并用RT-PCR的方法进一步证实目的 基因mRNA的表达水平.结果 RT-PCR获取编码T490基因的全序列cDNA,大小为508bp;DNA测序和PCR方法证实T490和EGFP融合基因成功克隆到真核超表达载体L;在荧光显微镜下,转染24h后的Hela细胞具有很强的绿色荧光;RT.PCR显示转染后的Hela细胞T490基因mRNA的表达明显.结论 重组质粒pDT490-EGFP构建成功,并在细胞内明显表达,此质粒可应用于研究睾丸特异性新基因T490的功能,为T490的生物学研究奠定基础.     

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.     

Systemic analgesia adapted to the children's condition

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.     

A comparison of the inhibitory effects of four volatile anaesthetics on the metabolism of chlorzoxazone, a substrate for CYP2E1, in rabbits

Background: Halothane inhibits in vitro and in vivo activity of cytochrome P-450 (CYP) 2E1. There are several fluorinated volatile anaesthetics besides halothane, and most of them are defluorinated by CYP2E1. It is unclear whether other fluorinated anaesthetics inhibit the in vivo activity of CYP2E1.
Methods: We compared the inhibitory effects of therapeutic concentrations of four inhalational anaesthetics, halothane, enflurane, isoflurane, and sevoflurane, on chlorzoxazone metabolism in rabbits receiving artificial ventilation.
Results: All four inhalational anaesthetics decreased arterial blood pressure and increased plasma chlorzoxazone concentration. However, no significant differences in the plasma chlorzoxazone concentration were found between the four anaesthetics. The estimated chlorzoxazone clearance increased after beginning inhalation with all four agents, but no significant difference in clearance was noted between agents.
Conclusions: At therapeutic concentrations, the in vivo inhibitory effect on chlorzoxazone metabolism was similar for all four inhalational anaesthetics examined, even though their chemical characteristics and extent of hepatic metabolism differ considerably.