丙泊酚对不同抗高血压治疗后高血压大鼠血流动力学和血管紧张素Ⅱ的影响

目的 探讨丙泊酚对不同抗高血压治疗后自发性高血压大鼠(SHR)血流动力学和血浆、心肌及主动脉中血管紧张素Ⅱ浓度的影响.方法 32只SHR随机分为四个抗高血压治疗组:卡托普利组(A组)、普荼洛尔组(B组)、双氧克尿塞组(C组)和非洛地平组(D组),每组8只.在抗高血压治疗12周后,大鼠以丙泊酚5 mg/kg诱导,继之以丙泊酚60 mg·kg-1·h-1持续输注30 min,观察输注期间MAP和HR变化,并于结束时处死大鼠,测定血浆、心肌及主动脉中血管紧张素Ⅱ浓度.结果 各组MAP、HR随着丙泊酚输注进行性下降和减慢,其中血流动力学抑制在A组最为明显.且A组各部位的血管紧张素Ⅱ浓度显著低于其它组(P<0.05).结论 丙泊酚麻醉对不同抗高血压治疗后高血压大鼠血流动力学有抑制作用,卡托普利治疗后抑制最明显;丙泊酚对血流动力学 抑制与体内血管紧张素Ⅱ浓度降低可能有关.     

c-fos在老龄自发性高血压大鼠肾脏的表达及缬沙坦干预作用

目的探讨老龄自发性高血压大鼠肾脏组织c-fos mRNA的表达及缬沙坦对其表达的影响。方法36只55周龄自发性高血压大鼠（SHR）随机分3组（n=12）：缬沙坦组（A组），贝那普利组（B组），对照组（C组），另设12只同龄WKY大鼠为正常对照组（D组）。定期检测尾动脉收缩压（SBP）；12周后：放射免疫法检测大鼠血浆血管紧张素Ⅱ（AngⅡ）、醛固酮（ALD）水平；RT-PCR法检测肾脏组织c-fos mRNA表达。结果与C组比较，A、B两组SBP显著下降，但A、B组间无显著差异；B组显著降低血浆AngⅡ水平，A组显著升高其水平；A、B两组均降低血浆ALD水平，A组较B组降低更显著；A、B两组不同程度地降低SHR肾组织c-fos mRNA表达，且以A组降低更为显著。结论贝那普利和缬沙坦均能够显著改善老龄自发性高血压大鼠肾脏组织重构，考虑其部分机制与下调c-fosm RNA表达有关。     

血液灌流联合血液透析对尿毒症难治性高血压患者的疗效

目的 探讨血液灌流联合血液透析对尿毒症难治性高血压患者的疗效.方法 将我院收治的46例尿毒症顽固性高血压患者按数字表法随机分为血液灌流组(n=23)和血液透析组(n=23).检测患者治疗前后血浆肾素活性、血管紧张素Ⅱ、甲状旁腺激素水平,观察血压变化情况.采用t检验或卡方检验进行数据统计.结果 治疗8周后,血液灌流组血浆肾素活性、血管紧张素Ⅱ、甲状旁腺激素及血压水平较治疗前有明显变化,差异有统计学意义(P＜0.05);而血液透析组治疗前后上述指标差异无统计学意义(P＞0.05).治疗后,两组上述指标差异有统计学意义(P＜0.05).结论 血液灌流联合血液透析能有效清除血浆肾素和血管紧张素,更好地控制尿毒症患者的难治性高血压.     

血管紧张素转换酶抑制剂在肾移植中的应用

血管紧张素转换酶抑制剂(ACEI)已广泛应用于临床,其对肾小球血液动力学的影响已逐渐被认识。肾移植术后常并发各种原因所致的高血压及蛋白尿,临床上应用TCEI进行治疗,但是如何正确应用,已成为人们关注的问题,本文就此综述如下: 一、ACEI对肾小球血液动力学及肾功能的影响肾素-血管紧张素-醛固酮系统(RAS)在体内调节动脉血压,肾脏血液动力学及水电解质平衡方面起着重要作用。由肾小球人球小动脉近端近球细胞分泌的肾素进入血液循环,作用于肝脏内产生的血管紧张素原,转化成血管紧张素Ⅰ,后者为+肽蛋白,必须在血管紧张素转换酶(ACE)的作用下,裂解成八肽的血管紧张素Ⅱ(AngⅡ),而AngⅡ则是RAS中起主要生物活性的物质之一。AngⅡ     

小凹蛋白-1在血管紧张素Ⅱ输注大鼠模型肾小球中表达及意义

目的观察血管紧张素Ⅱ输注大鼠模型肾小球小凹蛋白-1表达及分布,探讨小凹蛋白-1在肾小球损伤中的作用。方法18只雄性Wistar大鼠皮下埋置渗透性微泵,随机分为3组。A组为正常对照组,由生理盐水代替血管紧张素Ⅱ。B组用血管紧张素Ⅱ以400ng·kg^-1·min^-1持续输注28d。C组在B组基础上加用替米沙坦3mg·kg^-1·d^-1进行干预。每周末测量尾动脉收缩压、24h尿白蛋白定量,于28d处死大鼠。心脏采血,检测血肌酐。留取肾组织,光镜、电镜下观察肾组织病理学改变。免疫组织化学法、免疫荧光分别检测肾小球小凹蛋白-1表达及小凹蛋白-1磷酸化水平。结果（1）血管紧张素Ⅱ输注后,大鼠血压逐渐升高,尿蛋白持续增加,肾小球系膜区增生加重,替米沙坦治疗可以明显降低血压和减少尿蛋白,减轻肾小球系膜区增生。（2）血管紧张素Ⅱ输注大鼠肾小球小凹蛋白-1表达无明显改变,但其磷酸化水平明显增高,替米沙坦干预后小凹蛋白-1磷酸化水平明显降低。结论小凹蛋白-1在血管紧张素Ⅱ诱导肾损伤中可能发挥重要作用。     

5/6肾切除大鼠肾组织肾素-血管紧张素-醛固酮系统的昼夜节律

目的：研究慢性肾衰竭大鼠循环及肾局部肾素-血管紧张素-醛固酮（RAAS）的近日节律。方法：60只Wistar大鼠建立5/6肾衰竭大鼠模型,随机分为两组：肾衰组（A组,30只）,假手术组（B组,30只）。大鼠在恒温（22±2）℃,12：12h明（L）：暗（D）交替的环境中饲养12周。早上7：00开灯,记为ZT0时,依次类推,晚上19：00时关灯,记为ZT12时。在11周时留尿测24h尿蛋白定量。12周时分别留取血及肾标本。放免法检测血及肾脏肾素活性、血管紧张素Ⅱ（AngⅡ）及醛固酮（Ald）浓度。结果：与假手术组比较,肾衰组血肌酐水平及24h尿蛋白定量明显升高（P〈0.001）。无论是A组还是B组,肾组织肾素活性（KRA）、AngⅡ及Ald的近日节律与血浆中肾素活性（PRA）、AngⅡ及Ald节律不一致。如A、B组KPA的谷、峰值时间与PRA相反;血浆AngⅡ峰值时间A组在ZT20,B组在ZT16时,A、B组肾脏中AngⅡ峰值时间则在ZT4时。B组的血浆及肾RAAS各组分的近日节律与A组差异也有统计学意义。结论：大鼠肾局部RAAS节律与血浆中RAAS节律不同,慢性肾衰竭组RAAS节律与假手术组比较也发生改变。     

Perindopril对糖尿病大鼠肾小球病变保护作用机理的初步探讨

目的 了解血管紧张素转换酶抑制剂perindopril对糖尿病大鼠肾小球病变的保护作用及其机制。方法 观察perindopril对肾小球基底膜、系膜和尿蛋白的影响及血浆和肾组织肾素活性、血管紧张素Ⅱ(ATⅡ),肾组织血管紧张素原mRNA表达的改变。结果 糖尿病大鼠血浆及肾组织ATⅡ含量升高。perindopril有降低糖尿病大鼠尿蛋白、减慢肾小球毛细血管基底膜增厚的作用,但对系膜影响不大;血浆及肾组织肾素活性升高,ATⅡ含量降低,肾组织血管紧张素原mRNA表达增强。结论 perindopril对糖尿病肾小球病变有保护作用。此作用可能与perindo-pril降低血浆及肾组织肾素血管紧张素系统活性有关。     

全身热疗对血浆肾素血管紧张素Ⅱ和β2-微球蛋白浓度的影响

目的 观察晚期肿瘤患者行全身热疗对血浆肾素-血管紧张素系统(RAAS)和肾功能的影响.方法 择期晚期肿瘤患者行全身热疗20例,随机均分为全麻插管组(A组)和静脉麻醉组(B组),分别在加温前、加温至41.8℃维持60 min时(加温后)、复温至38℃(复温后)用放射免疫法测肾素活性(RA)、血管紧张素Ⅱ(AⅡ)和β2-微球蛋白(β2-MG)的浓度.结果 A组血浆RA浓度在加温后比加温前增高(P＜0.05),而AⅡ、β2-MG浓度稍有下降;B组血浆RA、AⅡ、β2-MG浓度在加温后均比加温前明显增高(P＜0.05),B组加温后RA、AⅡ、β2-MG浓度均高于A组(P＜0.05).结论 全麻插管能够抑制全身热疗高温刺激所致的RAAS反应.     

肾素系统在胰岛素抵抗性高血压中作用的探讨

目的：从肾素血管紧张素醛固酮系统（ＲＡＡＳ）角度初步探讨胰岛素抵抗（ＩＲ）时高血压及左室肥厚（ＬＶＨ）形成的可能机制。方法：以高蔗糖饲料喂养８周形成胰岛素抵抗高血压的大鼠（ＩＲＨＲ）（ｎ＝１３）和正常对照ＳＤ大鼠（ｎ＝１０）为研究对象，用放免技术测定了其循环和心肌组织ＲＡＡＳ各成分的变化。并了解其ＬＶＨ情况。结果：ＩＲＨＲ组血压、血清胰岛素（ＩＮＳ）、甘油三酯、醛固酮（ＡＬＤ）、左室相对质量、心肌组织肾素活性（ＲＡ）、血管紧张素Ⅱ（ＡｎｇⅡ）水平明显高于对照组；其胰岛素敏感性指数、血清高密度脂蛋白明显降低；其血浆ＲＡ、ＡｎｇⅡ与对照组相比无显著差异，光镜及电镜观察发现其左室心肌细胞明显肥大、间质胶原纤维明显增多。结论：高蔗糖饲料喂养ＳＤ大鼠可以形成胰岛素抵抗和高血压，并有脂质代谢紊乱，其高血压的形成可能与ＩＲ时     

全麻手术对肥胖患者血浆抵抗素和肾素血管紧张素及血糖的影响

目的　研究全麻诱导以及手术对肥胖患者血浆抵抗素 (resistin)和肾素、血管紧张素Ⅱ及血糖的影响。方法　选择 4 0例全麻手术患者 ,根据BMI指数分为两组 :A组 (BMI>2 5 ) 2 0例为肥胖者 ;B组 (2 1 相似文献   

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 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.     

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.     

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.