Comparative inotropic effects of local anesthetics in isolated cat papillary muscles

The direct inotropic action of seven local anesthetics: procaine, mapivacaine, lidocaine, tetracaine, chloroprocaine, bupivacaine and etidocaine were compared in isolated cat papillary muscles. All of the local anesthetics produced a dose-related depression of maximal velocity of shortening (Vmax), maximal developed force (Fm) and maximal dF/dt. The more potent local anesthetics such as bupivacaine and etidocaine depressed myocardial contractility at significantly lower concentrations than the less potent local anesthetics such as lidocaine and mepivacaine. Depression of Vmax by bupivacaine or etidocaine was three times greater than that by lidocaine and ten times greater than that by procaine. At the same concentration (10^–4M), direct myocardial depression was demonstrated in the following order of severity: etidocaine bupivacaine tetracaine chloroprocaine lidocaine mepivacaine procaine.(Kemmotsu O, Nakata F, Ueda M, et al.: Comparative inotropic effects of local anesthetics in isolated cat papillary muscles. J Anesth 4: 1–8, 1990)     

钙通道阻滞剂对低温保存大鼠肝脏的保护作用

目的：研究钙通道阻滞剂是否减轻低温保存下肝细胞的钙超载并起到保护肝脏的作用。方法：低温保存大鼠肝细胞于不同时限,按保存液的不同成分分组：（1）对照组：DMEM液;（2）实验Ⅰ组：DMEM液＋Verapamil(维拉帕米）;（3）实验Ⅱ组：DMEM液＋Nifedipine(硝苯地平）;（4）实验Ⅲ组：DMEM液＋Diltiazem(硫氮卓酮）。用Fura-2法测定低温保存下的大鼠肝细胞内钙和肝功能,并在光镜和电镜下观察肝脏的结构。结果：细胞内钙及肝功能测定,各实验组与对照组差异显著;组织学观察,保存0－48h各实验组损伤明显低于对照组。结论钙通道阻滞剂对低温保存肝脏有保护作用,且三类药物中帕米作用最强,硝苯地平和硫氮卓酮次之。     

The effects of calcium channel blockers on random skin flap survival in the pig model

Summary This study was designed to evaluate the influence of two calcium channel blockers, verapamil and nifedipine, on skin flap survival. These agents were selected because they inhibit the passage of calcium through calcium selective channels in the plasma membrane, thereby blocking calcium mediated electromechanical coupling in contractile tissue and resulting in peripheral arterial vasodilation. Three groups of pigs were used in this study. All skin flaps in this study were 3 cm wide and 12 cm long. The first group (10 flaps) served as controls with no pharmacologic manipulations. Pigs in group II (15 flaps) received verapamil (80 mg orally, three times a day) for 7 days postoperatively. Pigs in group III (15 flaps) received nifedipine (10 mg orally, three times a day) for 7 days postoperatively. Statistical analysis of the results demonstrated that both verapamil and nifedipine resulted in significant enhancement of skin flap survival. The increased survival of the skin flaps produced by nifedipine as compared to verapamil was statistically significant.This study is supported in part by PHS Research Grant DE00853 from the National Institute of Dental Research     

钙通道阻滞剂对重症急性胰腺炎大鼠血液流变学的影响

目的探讨钙通道阻滞剂对重症急性胰腺炎(SAP)血液流变学的影响.方法Wistar大鼠45只,随机分为A组,假手术组;B组,SAP组;C组,钙通道阻滞剂治疗组.观察各组血液流变学、酶学、胰腺及肺、肾的病理学改变.结果SAP时低切下全血粘度为(9.5±0.7)、红细胞聚集指数为(2.54±0.14)、红细胞刚性指数为(4.53±0.18),胰腺及胰外器官病理损害严重;治疗组上述各血液流变学指标分别为(7.8±0.5)、(2.17±0.12)、(4.01±0.13),与SAP组比较P值均＜0.05,胰腺及胰外器官的病理损害程度明显减轻(P＜0.05),且血液流变学异常与胰腺病理损害程度呈正相关(P＜0.05).结论钙通道阻滞剂能有效地改善SAP大鼠血液流变学异常,减轻胰腺及胰外器官的病理损害.     

钙通道阻滞剂的镇痛作用及其机制研究进展

背景 电压依赖性钙通道(voltage dependent calcium channels,VDCCs)参与了疼痛的发生及维持机制,钙通道阻滞剂在临床前及临床试验中显示出良好的镇痛作用. 目的 对主要的钙通道阻滞剂的镇痛作用及其机制进行回顾和总结. 内容 背根神经节(dorsal root ganglia,DRG)及脊髓背角感受伤害性刺激的神经元上有大量VDCCs分布,可调控去极化诱导的Ca2+内流,从而影响谷氨酸和P物质等与疼痛有关的神经递质释放.齐考诺肽等钙通道阻滞剂具有明确的镇痛作用,且不易形成耐受性及引起呼吸抑制,但给药途径受限,治疗窗狭窄. 趋向 钙通道阻滞剂的镇痛作用还需进行更深入的研究和探讨,从而开发更加安全方便的新型药物,为临床用药提供更多选择.     

The effect of calcium channel blockers on stone regrowth and recurrence after shock wave lithotripsy

We evaluated the possible effects of a calcium entry blocking agent “verapamil” on new stone formation and/or regrowth of residual fragments after shock wave lithotripsy (SWL) during long-term follow-up (>30 months) and compared the results with the success rates of adequate fluid intake. A total of 70 patients treated with SWL were randomly divided into three different groups, in the first two of which the patients received different preventive measures with respect to stone recurrence and/or regrowth. While 25 patients received a calcium channel blocking agent, verapamil hydrochloride, beginning 3 days before SWL and continued 4 weeks after the procedure, an additional 25 patients were put in an enforced fluid intake program and the remaining 20 patients received no specific medication and/or measure apart from close follow-up. Patients were followed regularly with respect to the clearance/regrowth of the residual fragments and that of new stone formation during long-term follow-up (within a mean follow-up of 30.4 months). The overall stone recurrence rate was 14% (10/70). Of the patients who became stone free (12/25, 48%) in group I, only one patient (1/12, 8.3%) showed a new stone formation during long-term follow-up. The figure was 40% (4/10) in group II patients and 55% (5/9) in group III patients receiving no specific medication. Regarding the residual stone fragments (<5 mm) after SWL, again high fluid intake was found to be the most effective on stone regrowth rates (2/13, 15.3%). Patients treated with verapamil also had acceptable regrowth rates (3/15, 20%). Finally, verapamil treatment significantly improved the clearance of residual fragments; while 7 out of 15 patients with residual fragments passed these particles successfully, (46.5%) in this group; these figures were 46% (6/13) and 18% (2/13) in the remaining groups. Residual fragments located in lower calyces demonstrated a poor clearance rate with higher regrowth rates. Verapamil administration was found to be effective enough to limit the regrowth of residual fragments and also to facilitate residual fragment clearance after SWL. Patients receiving this medication seemed to pass the retained fragments easily in a shorter time than the others.     

地尔硫卓及其复合异氟醚对大鼠心肌顿抑的影响

目的：探讨不同浓度地尔硫卓对大鼠顿抑心肌的保护作用和复合应用异氟醚的保护增强作用。方法：40只大鼠随机分成5组行Langendorff法离体心脏灌注。对照组（CONT）：仅经过缺血处理；地尔硫卓组（0．1DIL和0．5DIL）；于缺血前10min给予0．1μmol/L或0．5μmol/L地尔硫卓；地尔硫卓＋异氟醚组（0．1DIL＋I和0．5DIL＋I）；于缺血前10min给予地尔硫卓（0．1μmol/L或0．5μmol／L）和1．5MAC异氟醚。药物处理在缺血前即刻终止，缺血期20min，再灌注持续30min。记录分析左室收缩和舒张功能参数。结果；再灌注期CONT和0．1DIL组的DP、LV＋dp/dtmax和LV－dp/dtmax明显低于0．5DIL、0．1DIL＋I和0．5DIL＋I组（P＜0．05）；前两组的EDP明显高于后三组（P＜0．05）；各参数在后三组之间无明显差别（P＞0．05）。结论：地尔硫卓可有效地减轻心肌顿抑，吸入麻醉药异氟醚可增强低剂量地尔硫卓的保护作用。     

Negative inotropic effects of ATP on the isometric contractions of isolated rat heart muscle

The effects of ATP on the isometric contractions of isolated rat left ventricular papillary muscle were studied. Exogenously administered ATP had an immediate onset, an abrupt response, progressive recovery and produced dose-related depression in the peak developed tension, maximum rate of tension development and relaxation, which were statistically significant. There were no significant changes in the resting tension, time to peak tension and relaxation time, except for a significantly prolonged relaxation time at the highest concentration of ATP. In the studies of interactions of ATP and either epinephrine or Ca⁺⁺, we observed that ATP seemed to interfere with the inotropic effect of epinephrine, while Ca⁺⁺ antagonized the negative inotropic action of ATP. We conclude that the site of negative inotropic action of ATP is most likely on the cell membrane, where ATP interferes with Ca⁺⁺ flux, and that ATP interferes with the positive inotropic action of epinephrine.(Sohn YZ, Fukunaga AF, Katz RL: Negative inotropic effects of ATP on the isometric contractions of isolated rat heart muscle. J Anesth 2: 193–197, 1988)     

安氟醚及异氟醚对阿曲库铵临床药效的影响

目的：观察吸入１％安氟醚或等效浓度异氟醚对阿曲库铵临床药效的影响。方法：３０例择期手术病人随机分为三组，分别吸入６７％Ｎ２Ｏ（Ⅰ组），１％安氟醚（Ⅱ组）或０．６７％异氟醚（Ⅲ组）后观察阿曲库铵临床药效。结果：静注阿曲库铵０．５ｍｇ／ｋｇ后，Ⅰ、Ⅱ和Ⅲ组的起效时间分别是２．２±０．４２分、２．１±０．４２分和２．１±０．３４分（Ｐ＞０．０５），作用时间分别是４５．８５±３．７分、５５．２５±６．４７分和５５．８８±８．２５分（Ｐ＜０．０１）；维持９０％～９５％颤搐抑制所需阿曲库铵的静脉滴注速度分别为６．２７７±１．０９２μｇ·ｋｇ－１·ｍｉｎ－１、４．２７２±０．５８５μｇ·ｋｇ－１·ｍｉｎ－１和４．５０５±０．７１６μｇ·ｋｇ－１·ｍｉｎ－１（Ｐ＜０．０１）。结论：１％安氟醚及等效浓度的异氟醚均可增强阿曲库铵的临床药效，但两者之间的增强无显著差异。     

异氟醚和七氟醚麻醉对患者心率变异性的影响

目的研究异氟醚和七氟醚麻醉对患者心率变异性(HRV)的影响。方法60例择期颅脑手术患者,用动态心电图仪记录麻醉诱导前、插管后10 min、停药时、停药后1、2 h和4 h的HRV。结果ISO1组(异氟醚,年龄<60岁)和ISO2组(异氟醚,年龄≥60岁)插管后10 min、停药时、停药后1、2 h的低频功率(LF)、高频功率(HF)值均显著低于麻醉诱导前(P<0.05)。SEV1组(七氟醚,年龄<60岁)和SEV2组(七氟醚,年龄≥60岁)的LF、HF值在插管后10 min、停药时、停药后1 h均显著低于麻醉诱导前(P<0.05)。ISO组插管后各时点的LF、HF值均显著低于SEV组(P<0.05)。结论异氟醚对患者的交感神经和迷走神经都有明显的抑制作用,而对于交感神经和副交感神经活性的均衡性没有显著的影响。异氟醚对于交感神经和迷走神经的抑制作用比七氟醚更为明显。     

The effects of halothane, enflurane, and isoflurane on calcium current in isolated canine ventricular cells.

The effects of halothane, enflurane, and isoflurane on voltage-dependent Ca2+ channel current (ICa) were compared in canine ventricular cells by the whole-cell voltage-clamp technique. ICa was elicited in each cell by progressively depolarizing pulses, from -80 or -40 mV to more positive membrane potentials. The peak amplitude and inactivation rate of the inward current were analyzed before, during, and after the external application of equianesthetic concentrations (0.5, 1.0, and 2.0 MAC) of halothane, enflurane, or isoflurane. The concentrations of these agents in the Krebs' solution were as follows (percentage in the gas phase): halothane 0.36, 0.68, and 1.50%; isoflurane 0.50, 1.00, and 1.90%; and enflurane 0.66, 1.36, and 2.39%. Halothane, enflurane, and isoflurane rapidly reduced peak ICa amplitude at all voltages studied, resulting in a depression of the entire current-voltage relationship for ICa activation. This depression was concentration-dependent and completely reversible upon wash-out of the anesthetic agents. Quantitatively, the three anesthetic agents produced a similar inhibition of peak ICa at approximately equianesthetic concentrations. Inactivation of ICa during 200-ms depolarizing pulses was not affected by two lower concentrations of the anesthetic agents, but was accelerated by the highest concentration of enflurane used. These findings suggest that the negative inotropic and chronotropic actions of halothane, enflurane, and isoflurane on the ventricular myocardium are related, at least in part, to their inhibition of ICa at the sarcolemma. However, since all three anesthetic agents depressed ICa amplitude similarly, their quantitatively different effects on cardiac performance are due most likely to differences in actions at other cellular sites.     

The interaction of the calcium channel blockers verapamil and nifedipine with cyclosporin A in pediatric renal transplant patients

The elimination of cyclosporin A was assessed in eight pediatric renal transplant patients who received calcium channel blockers concomitantly with their immunosuppressive therapy. In three children, verapamil decreased the rate of elimination of cyclosporin A. In five children who received nifedipine, cyclosporin A elimination was also impaired, which contrasts with the reports in adult patients indicating that this calcium channel blocker has no effect on cyclosporin A elimination. When both calcium channel blockers were used on separate occasions in the same patient, nifedipine was less potent than verapamil in depressing cyclosporin A elimination. Although the number of subjects studied is small, these results likely indicate that nifedipine, as well as other calcium channel blocking drugs, must be used with caution in pediatric renal transplant patients.     

Effects of isoflurane and halothane on the calcium ion-tension curve in rat myocardium

In order to clarify the interaction of volatile anesthetics and extracellular calcium ion on the myocardial contraction, effects of both isoflurane (1.0%) and halothane (0.5%) on the extracellular calcium ion concentration ([Ca²⁺]_O)-tension curve were studied. Increasing [Ca²⁺]_O enhanced the myocardial contraction response, and the maximal response was obtained at [Ca²⁺]_O of 3.0mM. Halothane depressed the maximal value of the tension development in response to increasing [Ca²⁺]_O, while isoflurane did not (P 0.01). The probit response of the developed tension to the changes in [Ca²⁺]_O indicated that isoflurane increased the median effective concentration (EC₅₀) of [Ca²⁺]_O significantly from 0.484 ± 0.051 (mean ± SEM) to 0.870 ± 0.056mM (P = 0.001), but halothane did not (P = 0.018). Therefore, 1.0% isoflurane was concluded to move the [Ca²⁺]_O-tension curve to the right, while a downwards shift occurred with 0.5% halothane.(Saeki S, Hirakawa M, Shimosato S: Effects of Isoflurane and Halothane on the Calcium Ion-tension Curve in Rat Myocardium. J Anesth 6: 172–175, 1992)     

静吸复合麻醉下七氟醚与异氟醚对颅内压的影响

目的:在颅内顺应性正常神经外科病人,观察1.0 MAC七氟醚与异氟醚对颅内压的影响。方法:垂体瘤或颅咽管瘤手术病人16例,随机分为两组:A组为咪唑安定 芬太尼 1.0 MAC异氟醚;B组为咪唑安定 芬太尼 1.0 MAC七氟醚。选择L_(3～4)行蛛网膜下腔穿刺。麻醉诱导采用芬太尼-咪唑安定-阿曲库铵。插管后维持稳定30分开始吸入七氟醚(或异氟醚)。分别于麻醉前、吸入麻醉药前、达预定呼气末浓度30分内观察监测指标。结果:1.0 MAC七氟醚和异氟醚均可显著降低脑灌注压,异氟醚作用较强。吸入1.0 MAC七氟醚后颅内压首先呈显著性下降,15分后回复至基础水平。吸入1.0 MAC异氟醚后颅内压无显著性变化。结论:在颅内顺应性正常患者,1.0 MAC七氟醚和异氟醚均可安全用于神经外科麻醉。     

Combined effects of succinylcholine and calcium on membrane-bound acetylcholinesterase activity

The effects of succinylcholine and calcium (Ca²⁺), alone and together, on membrane-bound acetylcholinesterase (true-type cholinesterase) were examined using human erythrocyte ghosts to elucidate the combined pharmacological activity of succinylcholine and calcium in in vivo system. Succinylcholine inhibited the acetylcholinesterase by a mixed style. Calcium alone exhibited an inhibitory effect on the enzyme, but a biphasic effect together with succinylcholine: marked restoration of the enzyme activity at calcium concentrations lower than 6mM and depression at its higher concentrations. It is suggested that calcium induces a conformational change of the enzyme protein leading to the altered binding capacity of succinylcholine. In anesthetic practice, therefore, the use of calcium may not be indicated for the treatment of SCh phase II block.(Wakamatsu M et al.: Combined effects of succinylcholine and calcium on membrane-bound acetylcholinesterase activity. J Anesth 1: 15–21, 1987)     

丙泊酚靶控输注和异氟醚麻醉对罗库溴铵药效学的影响

目的比较丙泊酚靶控输注（TCI）复合雷米芬太尼全凭静脉麻醉和异氟醚复合雷米芬太尼麻醉对单次插管剂量罗库溴铵肌松效应的影响。方法ASAⅠ或Ⅱ级的择期全麻患者48例,随机均分为丙泊酚（P）组和异氟醚（I）组。麻醉诱导后予0.6mg／kg的罗库溴铵插管;P组和I组麻醉维持分别采用丙泊酚TCI-泵注雷米芬太尼和吸入1 MAC异氟醚-泵注雷米芬太尼。监测脑电双频指数（BIS）,使用加速度肌松监测仪观察拇内收肌的收缩反应,记录罗库溴铵的起效时间、无反应时间、肌松维持时间及恢复指数等指标。结果两组之间肌松起效时间、无反应时间及T1 25％时间差异无统计学意义,I组25％四个成串刺激比（TOFr）及恢复指数都比P组明显延长（P〈0．05）。结论单次插管剂量的罗库溴铵在丙泊酚TCI-泵注雷米芬太尼麻醉下肌松维持及恢复无明显变化,而在吸入1 MAC异氟醚-泵注雷米芬太尼麻醉下恢复时间明显延长。     

Effects of halothane and calcium entry blockers on atrioventricular conduction

The effects of halothane on AV nodal function were evaluated in dogs with verapamil, diltiazem, or nifedipine during atrial pacing using the technique of Hisbundle electrocardiography. Fifty-one mongrel dogs were divided into six groups. Anesthesia was induced with ketamine 100mg im. and thiamylal 25mg/kg iv. The animals were intubated and mechanically ventilated at normocapneic levels. Anesthesia was maintained with 50% nitrous-oxide in oxygen with pancuronium 2mg im. Dogs in groups I, III, and V were anesthetized with 0.8% halothane and 50% nitrous-oxide in oxygen. We observed interactions between halothane and intravenous administration of either verapamil 0.1mg/kg, diltiazem 0.15mg/kg, or nifedipine 0.01mg/kg respectively. Dogs in groups II, IV, and VI were administered either verapamil, diltiazem, or nifedipine iv without halothane. There were prolongations of sinus cycle length (SCL) (414 ± 10 to 542 ± 19msec.), atrium-His (AH) interval (73 ± 3 to 97 ± 5msec.), and functional refractory period (FRP) of the AV-node (227 ± 5 to 260 ± 5msec.) in halothane anesthesia in groups I, III, and V. There were more prolongations of these variables after iv administration of verapamil (SCL; 617 ± 35, AH; 118 ± 7, FRP of the AV node; 311 ± 4) and diltiazem (SCL; 554 ± 19, AH; 118 ± 12, FRP of the AV node; 283 ± 12) but no prolongations after nifedipine (SCL; 533 ± 19, AH; 99 ± 8, FRP of the AV node; 272 ± 9). Comparing effects of calcium entry blockers with and without halothane in groups I and II, III and IV, or V and VI, there were additive depressing effects of halothane with either verapamil or diltiazem on AV nodal function. And there is a difference between the effects of nifedipine on SCL with and without halothane.(Yokota S, Harada K, Takigawa C et al.: Effects of halothane and calcium entry blockers on atrioventricular conduction; A comparative study of verapamil, diltiazem, and nifedipine. J Anesth 2: 219–226, 1998)     

异氟醚、地氟醚对维库溴铵残余肌松作用的影响

目的　观测异氟醚、地氟醚对维库溴铵的残余肌松作用的影响。方法　选择 4 9例ASAⅠ～Ⅱ级成年择期全麻手术病人 ,随机分为三组 :丙泊酚组 (Ⅰ组 ,18例 ) ;异氟醚组 (Ⅱ组 ,17例 ) ;地氟醚组 (Ⅲ组 ,14例 )。全麻诱导气管插管后维库溴铵均以 90 μg·kg-1·h-1的速度静脉泵入。Ⅰ组丙泊酚泵入速度为 4～ 10mg·kg-1·h-1;Ⅱ组、Ⅲ组分别吸入呼气末浓度为 1MAC的异氟醚或地氟醚 ,使用Biometer加速度仪观测T1恢复至 2 5 %、75 %及TOF比值 (T4/T1)恢复至 0 7的时间。结果　三组间病人的性别、年龄、体重、身高、芬太尼总量、麻醉持续时间、血液动力学变化均无显著性差异 (P >0 0 5 )。上述恢复时间 ,Ⅱ组、Ⅲ组与Ⅰ组比较均延长 ,有显著差异 (P <0 0 5 ) ;Ⅱ、Ⅲ组比较差别无统计学意义 (P >0 0 5 )。三组间恢复指数 (T1从 2 5 %～ 75 %时间 )比较无显著差异 (P >0 0 5 )。结论　异氟醚、地氟醚均可延长维库溴铵的残余肌松作用 ,但两者比较无明显差别。临床应用中应注意监测四个成串刺激 (TOF)等 ,减少术后残余肌松作用所致的并发症     

钙通道阻滞剂对他克莫司血浓度的影响及临床意义

目的　探讨钙通道阻滞剂 (CA)对免疫抑制剂他克莫司 (FK50 6)血浓度的影响。方法　 (1 )将 2 0例肾移植患者平均分为 2组 ,观察组除服用FK50 6外 ,还同时服用钙拮抗剂维拉帕米 ;对照组不服用钙拮抗剂。分别检测并比较两组的FK50 6血浓度变化及其量化关系。 (2 )检测 1 0例肾移植患者服用钙拮抗剂维拉帕米前、后自身FK50 6血浓度变化及量化关系。结果　 (1 )观察组术后第 1 5d时的FK50 6血浓度为 (1 5 .8± 1 .3) μg/L ,对照组为 (1 0 .2± 1 .7) μg/L ,观察组比对照组平均升高 54 .9% ,P <0 .0 1 ;根据血浓度调整观察组术后不同时间内FK50 6服用量 ,比对照组平均减少2 7.1 %～ 50 .0 %。 (2 )观察组 1 0例肾移植患者加用维拉帕米前FK50 6用量为 (0 .0 6± 0 .0 2 )mg·kg- 1 ·d- 1 ,血药浓度为 (9.2± 1 .8) μg/L ,加用维拉帕米 1w后 ,FK50 6血浓度升至 (1 4 .1± 2 .9) μg/L ,其浓度平均升高了 53 .3 % ,此时调整FK50 6用量减少了 (0 .0 2± 0 .0 1 )mg·kg- 1 ·d- 1 ,减少幅度平均达 33 .3 %。结论　维拉帕米能提高肾移植患者FK50 6的血浓度 ,减少术后FK50 6的服用量 ,具有重大的临床应用价值及社会经济效益     

Comparison of the direct effects of sevoflurane,isoflurane and halothane on isolated canine coronary arteries

We have demonstrated previously, using dog epicardial arteries of different sizes, that isoflurane, like adenosine, is preferentially a small coronary artery dilator, whereas halothane, like nitroglycerin, is a large artery dilator. The present study was designed to compare the direct effects of sevoflurane with those of isoflurane and halothane. Proximal large coronary arteries with an outer diameter (o.d.) of 2.5–3.2 mm and distal small arteries of 0.6–0.9 mm o.d. were isolated from dogs and then cut into vascular rings. They were precontracted with KCl (20 mM), and their relaxant responses to anaesthetics were compared relative to the maximal responses induced by papaverine. Sevoflurane, halothane and isoflurane (1–3 human MAC) induced dose-dependent relaxation of these arteries. The relaxant response to sevoflurane did not differ between large and small arteries. However, the relaxant response of the large arteries to halothane (1.5–2.3%) was greater than that of small arteries (P < 0.01) and the response of small arteries to isoflurane (3.5%) was greater than that of large arteries (P < 0.05). In large arteries, the potency of the relaxant effect at equivalent human MAC could be ranked as halothane ≥ sevoflurane > isoflurane, and, in small epicardial arteries as isoflurane > sevoflurane ≫ halothane. We conclude that, unlike isoflurane, sevoflurane is not a preferential dilator of small coronary arteries. Nous avons déjà démontré sur des artères canines épicardiques de différents calibres, que l’isoflurane, comme l’adénosine est un dilatateur préférentiel des petites artères coronaires, alors que l’halothane, comme la nitroglycérine, est un dilatateur des grosses artères. L’étude présente vise à comparer les effets directs du sévoflurane avec ceux de l’isoflurane et de l’halothane. Chez le chien, on isole et sectionne en anneaux de grosses artères coronaires d’un diamètre externe de 2,5 à 3,2 mm et des petites artères coronaires distales de 0,6 à 0,9 mm. Elles sont préalablement contractées avec du KCl (20 mM) et leurs propriétés relaxantes en présence d’anesthésiques sont comparées à la réponse maximale provoquée par la papavérine. Il n’y a pas de différence entre le sévoflurane, l’halothane et l’isoflurane (MAC 1–3 humain); ils provoquent tous une relaxation artérielle qui dépend de la dose. L’effet relaxant du sévoflurane est identique que ce soit sur les grosses ou les petites artères. Cependant, la relaxation des grosses artères en réponse à l’halothane (1,5–2,3%) est plus importante que celle des petites artères (P < 0,01) et la réponse des petites artères à l’isoflurane (3,5%) est plus marquée que celle des grosses artères (P < 0,05). Pour les grosses artères, la puissance de l’effet relaxant à un MAC humain équivalent pourrait être classifiée dans l’ordre: halothane ≥ sévoflurane > isoflurane; et sur les petites artères épicardiques ainsi: isoflurane > sévoflurane ≫ halothane. Nous concluons que contrairement à l’isoflurane, le sévoflurane n’est pas un dilatateur préférentiel des petites artères coronaires.