糖皮质激素对大鼠肾上腺嗜铬细胞内游离钙离子浓度的影响

目的　研究糖皮质激素 (GC)对大鼠肾上腺髓质嗜铬细胞 (AMCC)分泌儿茶酚胺(CA)的作用机制。方法　用 5 μmol/L钙荧光染料fura 2AM负载体外培养的大鼠AMCC ,在激光扫描共聚焦显微镜 (LSCM )下实时测定地塞米松 (Dex)作用前后 ,KCl和尼古丁 (NIC)诱发细胞内[Ca2 + ] i 的变化。结果　 5 0 μmol/LDex对 60mmol/LKCl诱发大鼠AMCC内 [Ca2 + ] i的变化影响不大 ,差异无显著性 (P >0 .0 5 )。 5 0 μmol/LDex对 5 0 μmol/LNIC诱发细胞内 [Ca2 + ] i的变化有明显抑制作用 ,在灌洗 5和 10min时峰值抑制率分别为 (3 2 .9± 5 .2 ) %和 (3 5 .4± 6.0 ) %。结论　GC急性作用于大鼠AMCC ,对KCl所诱发的 [Ca2 + ] i升高无明显影响 ,但能明显抑制NIC所诱发细胞内 [Ca2 + ] i的升高 ,提示GC对大鼠AMCC分泌CA的急性效应可能与NIC受体有关     

依托咪酯对大鼠海马脑片突触长时程增强的影响

目的 评价依托咪酯对大鼠海马脑片突触长时程增强(LTP)的影响.方法 雄性SD大鼠,断头后取出海马组织,制备厚400 μm的海马脑片.采用细胞外微电极记录技术,记录海马脑片CA1区细胞外群体峰电位(PS).取42张脑片,随机分为6组(n=7):用正常的人工脑脊液(ACSF)灌流海马脑片记录正常的PS,待其稳定后,对照组继续灌流ACSF,不同浓度依托咪酯组分别用含依托咪酯1μmol/L(依托咪酯 1 μol/L组)、2/μmol/L(依托咪酯2 μmol/L组)、5 μmol/L(依托咪酯5 μmol/L组)、10μmol/L(依托咪酯10 μmol/L组)、20 μmol/L(依托咪酯20 μmol/L组)的ACSF灌流,记录PS幅值.另取84张脑片,随机分为12组(n=7):用正常ACSF灌流海马脑片,记录稳定正常的PS 30 min,LIT组继续灌流ACSF,其余各组分别用含依托咪酯l μmol/L(LTP-依托咪酯 1 μmol/L组)、2 μmol/L(LTP-依托咪酯2μmol/L组)、5 μmol/L(LTP-依托咪酯 5 μmol/L组)、10μmol/L(LTP-依托咪酯 10 μmol/L组)、20 μmol/L(LTP-依托咪酯20 μmol/L组)、印防己毒素50 μmol/L(印防己毒素组)、荷包牡丹碱10 μmol/L(荷包牡丹碱组)、CGP35348 5 μmol/L(CGP35348 组)、印防己毒素50 μmol/L+依托咪酯10 μmol/L(印防己毒素+依托咪酯组)、荷包牡丹碱10 μmol/L+依托咪酯10 μmol/L(荷包牡丹碱+依托咪酯组)、CGP35348 5 μmol/L+依托咪酯10 μmol/L(CGP35348+依托咪酯组)的ASCF灌流,记录PS 30 min后,施以100 Hz的高频刺激(HPS),记录PS幅值.结果 与LTP组比较,LTP-依托咪酯2 μmol/L组、LTP-依托咪酯5 μmol/L组、LTP-依托咪酯10 μmol/L组、LTP-依托咪酯20 μmol/L组和CGP35348+依托咪酯组HIS后PS幅值降低(P＜0.05或0.01),印防己毒素组、荷包牡丹碱组、CGP35348组HFS后PS幅值差异无统计学意义(P＞0.05);与依托咪酯LTP 10μmol/L组比较,印防己毒素+依托咪酯组和荷包牡丹碱+依托咪酯组HIS后PS幅值增加(P＜0.01).结论 依托咪酯可通过激活大鼠海马GABAA受体抑制LTP的形成,从而影响学习和记忆功能.     

异丙酚对兔离体气管平滑肌细胞内游离钙离子浓度的影响

目的 评价异丙酚对兔离体气管平滑肌细胞内游离钙离子浓度([Ca2+]i)的影响.方法 采用急性酶分离方法分离兔气管平滑肌细胞,采用随机数字表法,将细胞随机分为3组(n=5):异丙酚组(Ⅰ组,终浓度300 μmol/L)、异丙酚(终浓度300 μmol/L)+2-氨乙基硼酸二苯酯(终浓度40μmol/L)(Ⅱ组)和异丙酚(300 μmol/L)+斯里兰卡肉桂碱(终浓度10 μmol/L)(Ⅲ组).Ⅰ组加入终浓度300 μmol/L的异丙酚,孵育15 min后,用无钙的Hank平衡盐溶液冲洗3次,加入1μmol/L乙酰胆碱,记录[Ca2+]i.Ⅱ组加入终浓度40μmol/L的2-氨乙基硼酸二苯酯孵育15 min后,再加入终浓度为300μmol/L的异丙酚,与2-氨乙基硼酸二苯酯共同孵育15 min后,用无钙的Hank平衡盐溶液冲洗3次,加入1 μmol/L的乙酰胆碱.Ⅲ组加入终浓度10 μmol/L的斯里兰卡肉桂碱孵育15 min后,再加入终浓度为300μmol/L的异丙酚,与斯里兰卡肉桂碱共同孵育15 min后,用无钙的Hank平衡盐溶液冲洗3次,再加入1 μmol/L的乙酰胆碱.通过负荷钙离子荧光指示剂Fluo-3/AM测定气管平滑肌细胞内[Ca2+]i.结果 与Ⅰ组比较,Ⅱ组气管平滑肌细胞内[Ca2+]i差异无统计学意义(P＞0.05),Ⅲ组[Ca2+]i明显降低(P＜0.05).结论 异丙酚可降低兔离体气管平滑肌细胞内[Ca2+]i,其机制可能与抑制内质网1,4,5-三磷酸肌醇通路有关,而与内质网兰诺定通路无关.     

依托咪酯对猪肾上腺皮质细胞的毒性作用及依托咪酯预处理对其的影响

目的 探讨依托咪酯对猪肾上腺皮质细胞的毒性作用及依托咪酯预处理对其的影响.方法 实验分两部分,第一部分为细胞毒性实验,猪肾上腺皮质细胞随机分为8组,每组3皿,对照组加入0.5%二甲基亚砜(DMSO),其他7组分别加入50、100、200、300、400、500、1000 μmol/L依托咪酯,每组分别作用6、12、24 h,进行下述指标检测.第二部分为预处理实验,猪肾上腺皮质细胞随机分为3组,每组3皿,对照组加入0.5%DMSO,损伤组加入325 μmol/L依托咪酯作用24 h,预处理组先加入0.6 μmol/L依托咪酯作用1 h,洗脱后在培养基中孵育4 h,再加入325 μmol/L依托咪酯作用24 h.采用CCK-8法检测细胞活力,计算24 h时依托咪酯半数抑制浓度(IC50),采用流式细胞仪检测细胞凋亡情况.结果 依托咪酯可抑制猪肾上腺皮质细胞活力,诱导细胞凋亡,呈浓度和时间依赖性,24 h时IC50为325μmol/L.0.6 μmol/L依托咪酯预处理1 h可抑制325μmol/L依托咪酯诱发的细胞凋亡具有抑制作用.结论 依托咪酯通过诱发猪肾上腺皮质细胞凋亡对其功能产生抑制作用;依托咪酯预处理可减轻药物自身引起的这种抑制作用.     

依托咪酯对HL-60细胞的毒性作用及依托咪酯预处理对其的影响

目的探讨依托咪酯对人急性髓性细胞白血病细胞（HL-60细胞）的毒性作用,及依托咪酯预处理对此毒性作用的影响。方法实验分两部分,第一部分为细胞毒性实验,HL-60细胞随机分为6组,对照组不用依托咪酯处理,其他5组分别加入50、100、250、500、1 000μmol/L依托咪酯,每组分别作用4、8、12、24、48 h,进行下述指标检测。第二部分为预处理实验,HL-60细胞随机分为3组,对照组不用依托咪酯处理,依托咪酯组加入500μmol/L依托眯酯作用24 h,预处理组先加入1μmol/L依托咪酯作用1 h,洗脱后在培养基中孵育4 h,再加入500μmol/L依托咪酯作用24 h。采用MTT实验方法检测细胞活力,采用AnnexinⅤ-PI流式细胞仪检测细胞凋亡。结果依托咪酯可抑制HL-60细胞活力,诱导细胞凋亡,呈浓度和时间依赖性。1μmol/L依托咪酯预处理1 h,4 h后对500μmol/L依托咪酯作用24 h诱发的细胞凋亡具有抑制作用（P＜0．05）。结论依托咪酯通过诱发细胞凋亡,对HL-60细胞的功能产生了抑制作用,1μmol/L依托咪酯刺激1 h预处理可减轻药物自身引起的这种抑制作用。     

雄激素对前列腺癌细胞内游离钙离子浓度的影响

目的 探讨5α-双氢睾酮(DHT)对前列腺癌LNCaP细胞内游离钙离子浓度([Ca2+]i)的影响及其机制.方法 应用Fura-2/乙酸甲酯(Fura-2/AM)Ca2+荧光探针法结合MiraCal荧光成像系统实时检测不同浓度的DHT刺激以及Ca2+通道阻滞剂干预后LNCaP细胞[Ca2+]i的变化.结果 DHT能快速诱导[Ca2+]i升高,在20 s～3 min升至峰值.DHT浓度为1、10、100和1000nmol/L时能诱导[Ca2+]i分别从基础值(28±5)、(29±5)、(28±4)和(28±9)nmol/L上升至峰值31±3(P＞0.05)、65±9(P＜0.01)、193±33(P＜0.001)和(208±42)nmol/L(P＜0.001).DHT浓度为100和1000 mol/L时,[Ca2+]i峰值间差异无统计学意义(P＞0.05).细胞外液无Ca2+时,1000 nmol/L DHT未能诱导[Ca2+]i升高.细胞膜L-型电压门控Ca2+通道阻滞剂维拉帕米(50μmol/L)、地尔硫卓(100 μmol/L)或硝苯地平(5 mmol/L)37℃孵育细胞5 min后,能完全抑制1000nmol/L DHT诱导的[Ca2+]i升高.磷脂酶C抑制剂新霉素(1 mmol/L)37 ℃孵育细胞5 min或兰尼定受体阻滞剂普鲁卡因(50 mmol/L)37℃孵育细胞3 min后,对1000 nmol/L DHT诱导的[Ca2+]i升高没有影响.结论 DHT可快速、剂量依赖性诱导LNCaP细胞[Ca2+]i升高;DHT诱导LN-CaP细胞[Ca2+]i的升高是细胞外Ca2+经细胞膜L-型电压门控Ca2+通道流入细胞内实现的,细胞内贮钙库未释放Ca2+.     

粉防己碱对新西兰白兔阴茎海绵体平滑肌细胞内游离钙离子浓度的影响

目的探讨粉防己碱(Tet)松弛阴茎海绵体平滑肌的作用机制。方法体外培养的第3～4代新西兰白兔阴茎海绵体平滑肌细胞,经钙荧光指示剂Fluo-2/AM负载后,用荧光离子数字成像系统观察Tet对平滑肌细胞内[Ca~(2 )]i的影响。结果Tet对平滑肌细胞内静息[Ca~(2 )]i无明显影响(P>0.05)。在细胞外钙浓度为2.5 mmol/L时,1、10和100μmol/LTet对高钾和去氧肾上腺素(PE)引起的细胞内[ca~(2 )]i升高有浓度依赖性地抑制作用。对40 mmol/L KCl引起的细胞内[Ca~(2 )]i升高的抑制率分别为22.0%、41.0%和73.0%(P<0.05)。对10μmol/L PE引起的细胞内[ca~(2 )]i升高的抑制率分别为15.0%、26.4%和46.6%(P<0.05)。在无细胞外钙时,1μmol/L和10μmol/L Tet对PE引起的细胞内[Ca~(2 )]i升高,无明显影响(P>0.05);而100μmol/L Tet能明显抑制PE引起的细胞内[ca~(2 )]i升高,抑制率为28.2%(P<0.05)。结论Tet可能通过阻滞电压依赖性钙通道、α1受体依赖性钙通道和抑制细胞内钙库释放,降低阴茎海绵体平滑肌细胞内[Ca~(2 )]i水平,这是Tet松弛阴茎海绵体平滑肌的作用机制之一。     

川芎嗪对家兔阴茎海绵体平滑肌细胞游离钙浓度的影响

目的 :研究中药川芎嗪 (TMP)对体外培养家兔阴茎海绵体平滑肌细胞 (PCSMC)胞质内游离钙浓度([Ca2 + ] i)的影响。　方法 :用新型Ca2 + 荧光染色剂Fluo 3/AM负载家兔PCSMC ,细胞分为氯化钾 (KCl)作用组和去甲肾上腺素 (NE)作用组 ,应用激光扫描共聚焦显微镜 (LSCM)实时测定胞质内 [Ca2 + ] i的变化 ,分别观察不同浓度的TMP对高钾和NE诱导胞质内 [Ca2 + ] i升高的影响 ,并与经典钙拮抗剂维拉帕米 (Ver)的作用相对比。　结果 :静息状态下 ,TMP对家兔PCSMC胞质内 [Ca2 + ] i无明显影响。 1、1 0、1 0 0 μmol/LTMP能显著抑制高钾诱发的细胞内 [Ca2 + ] i升高 ,抑制率分别为 (38.6± 3 .0 ) %、(44.1± 2 .4) %和 (53 .7± 4 .1 ) % ;也能抑制 1 μmol/LNE诱发钙库释放所致的细胞内 [Ca2 + ] i升高 ,抑制率分别为 (1 3 .9± 2 .7) %、(2 1 .2± 1 .9) %和 (2 9.5± 3 .6) %。　结论 :TMP通过对家兔PCSMC电压依赖性钙通道和细胞内钙库释放的双重抑制作用 ,降低PCSMC胞质内 [Ca2 + ] i水平 ,其作用效果与Ver相似 ,这是TMP治疗阴茎勃起功能障碍的重要机制。     

烧伤血清对大鼠心肌细胞钙稳态的影响

目的　观察烫伤血清对成年大鼠分离的心肌细胞游离钙浓度 [(Ca2 )i]及胞膜钙通道电流的影响 ,探讨烧伤引起的心肌细胞钙稳态变化。　方法　伤后 2、4、6h分离 30 %TBSAⅢ度烧伤SD大鼠血清 ,简称 2hBS、4hBS、6hBS ;逆行循环灌流、胶原酶消化分离心肌细胞 ;Fura - 2 /AM荧光染色法测定 [Ca2 ]i;膜片钳技术全细胞记录模式测定细胞膜钙通道电流。　结果　正常心肌细胞[Ca2 ]i为 (10 1.3± 2 1.3)nmol/L ,烧伤血清可使心肌细胞 [Ca2 ]i显著升高。 (P <0 .0 1) ,以 6hBS的作用最强 ;钙通道阻断剂异搏定 (30mmol/L)和肌浆网rynodine受体拮抗剂普鲁卡因 (2mmol/L)均非常显著地抑制 6hBS的作用 (P <0 .0 1) ,抑制率分别为 47.7%和 6 7.6 % ,后者强于前者 (P <0 .0 1) ,2hBS使峰值L型钙电流 (ICa -L)比对照组增加 5 0 80 % ;而 6hBS使峰值ICa -L增加 1 5 2 .5倍 ;峰值电流 -电压曲线显示烧伤血清明显增加各个去极化钳制电压下的ICa ,并使得最大激活电压提前 ;细胞外液灌洗可祛除烧伤血清对钙电流的作用。　结论　烧伤血清能使心肌细胞 [Ca2 ]i,和膜上钙通道电流显著升高 ,钙稳态变化可能是烧伤后心肌损害的一种细胞机制     

家兔阴茎海绵体平滑肌细胞内游离钙检测方法的对比研究

目的　通过对家兔阴茎海绵体平滑肌细胞 (PCSMC)内游离Ca2 检测方法的对比 ,以选择更适宜的方法来研究阴茎海绵体平滑肌的舒张机制。方法　采用新型Ca2 荧光探针Fluo 3/AM标记家兔PCSMC胞浆内游离Ca2 ,应用显微分光光度计 (MSP)、流式细胞仪 (FCM)和激光扫描共聚焦显微镜 (LSCM)分别观察硝苯吡啶 (NIF)对高K 诱发家兔PCSMC内 [Ca2 ]i 变化的影响。结果　MSP和FCM检测发现 ,10 μmol/LNIF能明显减弱高K (4 0mmol/L)诱发细胞内荧光强度的升高 ,抑制率为 (6 5 .5± 4 .4 ) %和 (6 9.3± 5 .2 ) %。LSCM可见细胞胞浆内游离Ca2 分布 ,不同细胞胞浆内的基础荧光强度有差别 ,NIF能明显抑制高K 诱发的细胞内 [Ca2 ]i 升高 ,抑制率为 (71.5±6 .8) %。结论　LSCM能直观地看到单细胞内Ca2 的分布 ,并能动态观察胞浆内 [Ca2 ]i 的变化 ,为研究不同药物对PCSMC的影响提供了良好的实验方法。     

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.     

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.     

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.