可乐定镇痛与中枢Ca~(2+)的关系

用大鼠甩尾法和放射配基结合实验,探讨了可乐定镇痛与中枢Ca~(2+)的关系。CaCl_2(1μmol/rat,icv)和EGTA(0.2μmol/rat,icv)分别拮抗和增强可乐定(1mg/kg,sc)的镇痛。戊脉安(0.1μmol/rat,icy)对可乐定(1 mg/kg,sc)镇痛无明显影响,但可部分翻转CaCl_2对可乐定镇痛的拮抗。CaCl_2(1×10~(-3)mol)对[~3H]-可乐定结合无明显抑制。结果表明可乐定镇痛与脑室周围组织中Ca~(2+)浓度变化密切相关,Ca~(2+)至少部分需经对戊脉安敏感的钙通道进入细胞内方可拮抗可乐定镇痛。推沦:可乐定镇痛与神经元内Ca~(2+)有关。     

可乐定抑制胃肠运动及机理研究

可乐定(15～120μg/kg,sc)剂量依赖式地抑制小鼠及大鼠胃肠推进运动及小鼠排便反射,此作用明显强于吗啡。可乐定(120μg/kg·d×10d,sc)对小鼠上述作用未产生耐受性。icv可乐定(12μg/kg)抑制大鼠胃肠推进运动作用强于sc同剂量的可乐定。育亨宾(0.5～5mg/kg,sc)剂量依赖式地拮抗可乐定对小鼠胃肠推进运动及排便的抑制作用。     

可乐定镇痛与中枢胆碱能系统关系的研究

本文通过小鼠光辐射热甩尾实验证明毛果芸香碱对可乐定镇痛具有增强作用,而阿托品则具有拮抗作用。阿托品对可乐定镇痛的拮抗可能不是通过竞争受体的机制,因阿托品只有达10~(-4)M/L时方可减少(~3H)-可乐定的特异性结合。给大鼠侧脑室注射密胆碱(30μg/只)明显减弱可乐定(2mg/kg,S·C)的镇痛效应。结果提示可乐定镇痛效应的充分发挥需要中枢胆碱能系统功能的完整。     

可乐定治疗海洛因依赖125例临床心电图分析

目的··:探讨可乐定对心率及心脏传导功能的影响。方法··:分析125例海洛因依赖者应用可乐定脱毒治疗中及治疗后的心电图变化。结果··:心律失常75例,发生率60%,全部为缓慢型心律失常。结论··:可乐定对心率及心脏传导功能有一定抑制作用,但不影响脱毒治疗,是比较安全的非阿片类戒毒药。     

可乐定对小鼠和猫实验性脑缺血的保护作用

可乐定0.03～1.0 mg·kg~1可显著延长双侧颈总动脉结扎致脑缺血小鼠的存活时间,生理盐水(NS)组平均存活6.1 min,而可乐定0.03 mg·kg使存活时间延长3倍,1.0 mg·kg~1时则延长15倍可乐定也显著提高脑缺血后再灌流小鼠生存数,延长双侧颈总动脉和双侧推动脉结扎致急性脑缺血猫的存活时间及脑电图(EEG)变平坦的时间,减少猫脑缺血时心律失常的发生。     

高效液相色谱法测定盐酸可乐定脉冲释药微丸胶囊的含量

目的 建立盐酸可乐定脉冲释药微丸胶囊中盐酸可乐定的含量测定方法.方法 采用高效液相色谱法,色谱柱为Diamonsil C8柱(250 mm×4.6 mm,5μm),流动相为0.22%辛烷磺酸钠-甲醇-磷酸(500:500:1,用1 mol/L氢氧化钠溶液或磷酸调pH至3.0),流速为1.0mL/min,检测波长为220nm.结果 盐酸可乐定质量浓度在10.24～122.88 μg/L范围内与峰面积线性关系良好(r=0.9992);盐酸可乐定的平均回收率为99.73%,RSD=0.60%(n=9).结论 该法灵敏快速、准确可靠,可作为盐酸可乐定脉冲释药微丸胶囊中盐酸可乐定的含量测定方法.     

中毒患者血液中可乐定液相色谱-质谱检测方法的研究

目的建立人血液可乐定LC-MS/MS定性定量检测的方法,用于可乐定中毒患者的诊断。方法取患者静脉全血,分离血清500μl加1 000μl乙腈混匀,离心沉淀,上清液用针头滤器过滤,取10μl进样。在串联四级杆质谱ESI正离子电离模式下,监测m/z 230.1/212.8和230.1/160.1两对MRM离子对进行可乐定检测。分析保留时间(RT),确定线性范围,计算检出限、精密度和稳定性。结果可乐定保留时间为4.4 min,在1~800 ng/ml的范围内线性关系良好(r=0.9991),最低定量限(LOQ)为0.2 ng/ml,日内精密度RSD为3.9%,日间精密度RSD为5.5%,平均回收率为47.6%,可乐定在室温环境中较为稳定。结论本研究建立LC-MS/MS检测可乐定的方法灵敏、快速,特异性好,适用于临床可乐定中毒患者的诊断与指导治疗。     

可乐定镇痛与中枢Ca2+的关系

用大鼠甩尾法和放射配基结合实验,探讨了可乐定镇痛与中枢Ca²⁺的关系。CaCl₂(1μmol/rat,icv)和EGTA(0.2μmol/rat,icv)分别拮抗和增强可乐定(1mg/kg,sc)的镇痛。戊脉安(0.1μmol/rat,icy)对可乐定(1 mg/kg,sc)镇痛无明显影响,但可部分翻转CaCl₂对可乐定镇痛的拮抗。CaCl₂(1×10^-3mol)对[³H]-可乐定结合无明显抑制。结果表明可乐定镇痛与脑室周围组织中Ca²⁺浓度变化密切相关,Ca²⁺至少部分需经对戊脉安敏感的钙通道进入细胞内方可拮抗可乐定镇痛。推沦:可乐定镇痛与神经元内Ca²⁺有关。     

全固态可乐定电极的制备和应用

对以四苯硼酸-可乐定离子缔合物为活性材料的可乐定选择性涂丝电极的性能进行了研究,并与PVC 膜可乐定电极的性能作了比较,探讨了影响涂丝电极稳定性的因素。其线性范围1.0×10~(-1)～2.0×10~(-6)mol/L,平均斜率57.1mV/decade,检测下限5.0×10~(-7)mol/L,有较理想的选择性。     

心脉康胶囊药效学研究

心脉康200、400mg/Kg ig小鼠,一日一次,连续7天,能明显延长小鼠耐缺氧时间,显著提高地尔硫(艹卓)引起小鼠缓慢型心律失常的心率,同时能明显降低死亡率。心脉康400、800mg/Kg一次ig大鼠,对可乐定引起的缓慢型心律失常具有明显的治疗作用,可显著提高大鼠心率,减少心率变异指数,降低房室传导阻滞发生率,改善房室传导功能。     

Epicardial controlled-release verapamil prevents ventricular tachycardia episodes induced by acute ischemia in a canine model.

Sustained-release preparations composed of verapamil-polymeric controlled-release matrices were characterized in vitro and utilized as epicardial implants in dogs with ischemic ventricular arrhythmias. Anesthetized open-chest dogs were subjected to 5 hourly, 10-min complete occlusions of the left anterior descending coronary artery followed by reperfusion. A controlled-release matrix preparation (20% verapamil, 80% polyurethane), placed on the left ventricular epicardium prior to the third occlusion, resulted in successful inhibition of ventricular tachycardia (VT) during acute ischemia in a dose-dependent manner. The largest matrix size used, 300 mg (20% verapamil), provided a net systemic dose of 0.52 +/- 0.18 mg/kg over 140 min and significantly reduced VT episodes during acute ischemia (fifth occlusion) compared to untreated controls (0.16 +/- 0.04 vs. 1.01 +/- 0.35 episodes/min, respectively; t = 2.62, p = 0.01). In controls, by the fifth occlusion ventricular fibrillation (VF) occurred after 5.41 +/- 0.78 min in 89% of animals. However, after a 300-mg verapamil matrix was placed on the left ventricular ischemic zone, VF occurred in only 45% (chi-squared = 4.1, p = 0.04, vs. controls) of the animals after 7.87 +/- 0.92 min (fifth occlusion). Systemic venous plasma verapamil levels during the 2 h following the 300-mg matrix ischemic zone implantation ranged from 8.4-22.0 ng/ml, while simultaneous regional coronary venous levels were 125.0-387.0 ng/ml. Sonomicrometry studies of left ventricular wall thickening carried out with a series of 300-mg verapamil matrix cardiac implants did not demonstrate any significant myocardial dysfunction. It is concluded that controlled-release verapamil, administered directly to the heart, was effective for preventing VT and VF associated with acute coronary ischemia, and that this route of administration was not associated with any significant deterioration of cardiac function.     

The effects of Z13752A, a combined ACE/NEP inhibitor, on responses to coronary artery occlusion; a primary protective role for bradykinin

The effects on the responses to coronary artery occlusion of a combined ACE/NEP inhibitor (Z13752A) were examined in anaesthetized dogs. A 1 h infusion of Z13752A (128 microgram kg(-1) min(-1) intravenously) decreased arterial blood pressure (by 11+/-3%; P<0. 05) and increased coronary blood flow (by 12+/-4%, P<0.05). There were no other significant haemodynamic changes. Z13752A inhibited both NEP and ACE enzymes both in dog plasma and in tissue (lung ACE; kidney NEP). Pressor responses to angiotensin I in vivo were inhibited and systemic vasodilator responses to bradykinin were potentiated. When the left anterior descending coronary artery was occluded for 25 min, Z13752A markedly reduced the severity of the resultant ventricular arrhythmias. No ventricular fibrillation (VF) occurred (compared to 7/16 in the controls; P<0.05), and ventricular tachycardia (VT) was reduced (VT in 2/9 dogs treated with Z13752A cp. 16/16 of controls; episodes of VT 0.2+/-0.1 c.p. 10.7+/-3.3; P<0. 05). Reperfusion of the ischaemic myocardium led to VF in all control dogs but occurred less frequently in dogs given Z13752A (survival from the combined ischaemia-reperfusion insult 67% c.p. 0% in controls; P<0.05). Z13752A reduced two other indices of ischaemia severity; epicardial ST-segment elevation and inhomogeneity of electrical activation. These protective effects of Z13752A during ischaemia and reperfusion were abolished by the administration of icatibant (0.3 mg kg(-1), i.v.) a selective antagonist of bradykinin at B(2) receptors; the ischaemic changes in dogs given both icatibant and Z13752A were similar to those in the controls. We conclude that this ACE/NEP inhibitor is effective at reducing the consequences of coronary artery occlusion in this canine model and that this protection is primarily due to potentiation of released bradykinin.British Journal of Pharmacology (2000) 129, 671 - 680     

REPERFUSION ARRHYTHMIAS IN CLOSED-CHEST RATS: THE EFFECT OF MYOCARDIAL NORADRENALINE DEPLETION AND Ca2+-ANTAGONISM

1. The influence of myocardial noradrenaline depletion on the incidence and severity of reperfusion arrhythmias in closed-chest anaesthetized rats was investigated. Five-minute left coronary artery occlusion was carried out via an implanted occluder. Four groups of rats were studied: controls, rats treated with reserpine (5 mg/kg, intraperitoneally) 24 h before occlusion, and rats receiving 0.2 mg/kg gallopamil intravenously 5 min before occlusion either with or without reserpine pretreatment. 2. In the control group all animals had ventricular tachycardia (VT) and fibrillation (VF) immediately after reperfusion. Gallopamil reduced VT to 50% and VF to 25% (P less than 0.05 versus control). In the reserpine group all had VT, and 67% had VF, this being not significantly different from controls. Additional treatment with gallopamil markedly reduced VT and totally prevented VF (P less than 0.05 versus control). 3. Thus, total depletion of myocardial noradrenaline stores neither prevented the occurrence nor reduced the severity of reperfusion arrhythmia in rats, while gallopamil treatment was effective.     

Pretreatment with a single bolus injection of polyoxyethylene-modified superoxide dismutase prevents reperfusion induced arrhythmias in the anesthetized rat

Effects of a newly introduced polyoxyethylene-modified superoxide dismutase (SOD-POE) on reperfusion induced arrhythmias were examined in the pentobarbital anesthetized rat. Reperfusion induced arrhythmias were elicited by occlusion of the left anterior descending coronary artery (LAD) for 15 min and subsequent release. The LAD occlusion was performed by compressing the artery using a suction cup of 2 mm in diameter placed on the LAD to which negative pressure was applied. The LAD occlusion and release was repeated at an interval of 30 min. SOD-POE or human SOD (h-SOD) (1000 U/kg) was injected intravenously 15 min prior to the occlusion at the second trial of the occlusion. In the control group, various types of arrhythmias including ventricular fibrillation (Vf), ventricular tachycardia (VT), premature ventricular contraction (PVC) and premature atrial contraction (PAC) were elicited immediately after release of the occlusion. In the SOD-POE-treated group, Vf and VT were completely prevented and the numbers of PVC and PAC significantly decreased, while pretreatment with h-SOD did not prevent the occurrence of reperfusion induced arrhythmias. The protective effects of SOD-POE lasted for more than 90-120 min. The plasma half life for SOD-POE was 10.8 hr, while that for h-SOD was 8.6 min. Results indicate that intravenous administration of SOD-POE would provide a new means of preventing reperfusion induced arrhythmias occurring in clinical situations.     

The role of mitochondrial K(ATP) channels in antiarrhythmic effects of ischaemic preconditioning in dogs

1. In the canine a single brief (5 min) coronary artery occlusion protects the myocardium against the severe ventricular arrhythmias and reduces the ischaemic changes that result from a subsequent, more prolonged (25 min) occlusion. The main purpose of the present study was to examine whether mitochondrial K(ATP) channels are involved in this protection. 2. In chloralose-urethane anaesthetized dogs, preconditioning (PC) was induced by a single 5 min period occlusion of the left anterior descending (LAD) coronary artery, 20 min prior to a 25 min occlusion of the same artery. In some of these PC dogs 5-hydroxydecanoate (5-HD; 150 micro g kg(-1) min(-1) by intracoronary infusion) was given over a period of 30 min either before, or after PC. In other dogs the mitochondrial K(ATP) channel opener diazoxide (1 mg kg(-1); i.c.) was given, either alone or in the presence of 5-HD. Control dogs (infused with saline) were simply subjected to a 25 min occlusion and reperfusion. 3. Compared to controls, both PC and diazoxide significantly reduced the number of ventricular premature beats (VPBs; 295+/-67 to 89+/-28 and 19+/-11, respectively; P<0.05), the number of episodes of ventricular tachycardia (VT; 8.3+/-4.2 to 1.6+/-0.9 and 0.2+/-0.1; P<0.05) and the incidences of VT (100 to 43 and 33%; P<0.05) and ventricular fibrilation (VF; 60 to 0 and 17%; P<0.05) during the 25 min occlusion of the LAD. Further, 43% of the PC dogs and 58% of the diazoxide treated dogs survived the combined ischaemia-reperfusion insult (cp. 0% in the controls; P<0.05). The protection afforded by PC and diazoxide was abolished by 5-HD, especially when it was given prior to the PC occlusion. In the presence of 5-HD, three out of 10 dogs fibrillated during the PC occlusion and another three dogs died following reperfusion. Furthermore, there were no survivors in this group from the prolonged ischaemia/reperfusion insult. 5-HD given after PC only attenuated the antiarrhythmic protection. 4. Opening of mitoK(ATP) channels prior to ischaemia by preconditioning and diazoxide protects the myocardium against ischaemia and reperfusion-induced arrhythmias. This protection is abolished if the opening of these channels is prevented by the prior administration of 5-HD but only attenuated if 5-HD is given after preconditioning. The results indicate that opening of mitoK(ATP) channels prior to ischaemia is mandatory for protection against ischaemia and reperfusion-induced arrhythmias.     

Anesthetized rabbit as a model for ischemia- and reperfusion-induced arrhythmias: Effects of quinidine and bretylium

Experiments were performed to assess the feasibility of using anesthetizes rabbits for the study of ischemia- and reperfusion-induced arrhythmias. Initial studies indicated that occulusion of the left anterior descending coronary artery produced ectopic activity in only one out of eight rabbits. All rabbits subject to occlusion of the left circumflex artery below where it emerges from under the left atrial appendage had ECG changes (ST-segment elevation, Lead II), 80% had arrhythmias, and 50% died in ventricular fibrillation during the first 20 min of coronary artery occulusion. Subsequent reperfusion in the survivors produced further arrhythmias in the majority of rabbits, and one fibrillated. Although a high incidence of ectopic activity was also observed in rabbits subject to occlusion of the left circumflex artery close to its origin, or both the left anterior descending and circumflex arteries, this was accompanied by marked reductions in arterial blood pressure. Thus, occlusion of the left circumflex artery at the lower site was chosen for all further studies. Quinidine hydrochloride 10 mg kg⁻¹ (n = 1) or bretylium tosylate 20 mg kg⁻¹ (n = 10) administered 15 min prior to coronary artery occlusion reduced the incidence of ischemia-induced ventricular fibrillation to 10% compared with 60% in controls (n = 15). Although bretylium reduced arterial blood pressure and heart rate, neither drug altered the hemodynamic consequences of coronary artery occulusion (e.g., increased left ventricular end diastolic pressure). Bretylium at doses of 5 and 20 mg kg⁻¹, but not quinidine, reduced the ST-segment elevation that developed during the ischemic period. The ability to detect the antifibrillatory activity of quinidine and bretylium suggests that the anesthetized rabbit may provide a useful alternative or additional model for the study of arrhythmias induced by acute myocardial ischemia.     

Effects of different preproendothelin-1 mRNA anti-sense oligodeoxynucleotides on ischemic arrhythmias in rats

The effects of four anti-sense oligodeoxynucleotides (AS-ODNs) against rat or human preproendothelin-1 mRNA on ischemic arrhythmias in anesthetized rats were studied. AS-ODN (60 nmol/kg) or control (normal saline; sense-ODN, and scrambled-ODN, 60 nmol/kg) was injected 2 h before acute myocardial ischemia elicited by the occlusion of the left anterior descending coronary artery. Arrhythmias during 60-min ischemia were assessed, and plasma endothelin-1 was determined with an endothelin-1-specific radioimmunoassay system. The results showed that anti-senses against human preproendothelin-1 mRNA were anti-arrhythmic without significant impact on hemodynamics, whereas two against rat preproendothelin-1 mRNA and the three controls failed to be anti-arrhythmic. In human antisense groups, both the incidence of reversible ventricular fibrillation and the mortality were decreased to zero. The incidences of ventricular tachycardia and salvos were significantly decreased from almost 100% in the controls to < or =30% (p < 0.01), the arrhythmia score from an average of approximately 3.6 to 0 and 0.7, respectively (p < 0.01 versus controls), and the total ventricular ectopic beats from an average of 307-338 to < 40 (p < 0.01). The human AS-ODNs led to less plasma endothelin-1, which was associated with suppressed ischemic arrhythmias in this rat model, indicating a contributory role of endothelin-1 in ischemic arrhythmias. Conversely, considering the two- or three-base mismatches between the human AS-ODNs and rat preproendothelin-1 mRNA, and the failure of the rat AS-ODNs in suppressing arrhythmias, the possibility could not be excluded that human endothelin-1 AS-ODNs acted via an undetermined pathway other than endothelin-1.     

Ventricular arrhythmias parallel cardiac histamine efflux after coronary artery occlusion in the dog

Release of cardiac histamine by immunologic and pharmacologic stimuli is known to provoke ventricular arrhythmias. Augmented histamine efflux from ischemic myocardium has been proposed but remains controversial. The purpose of this study was to determine whether cardiac histamine efflux is precipitated by coronary artery occlusion and if so, whether histamine efflux is associated with the development of early ischemic ventricular arrhythmias. The left anterior descending coronary artery was occluded while recording a continuous electrocardiogram and coronary sinus blood was sampled frequently during the first 30 min of coronary artery occlusion in pentobarbital-anesthetized, open-chest dogs. Coronary sinus histamine concentration rose from a mean baseline of 0.06 +/- 0.10 ng/ml (+/- SD) before coronary artery occlusion to a mean peak of 0.61 +/- 0.40 ng/ml after coronary artery occlusion (p less than 0.0001; n = 14). The median peak coronary sinus histamine concentration was significantly greater in dogs that suffered ventricular fibrillation after coronary artery occlusion (n = 4) than in those that did not (n = 10) (0.86 ng/ml vs. 0.37 ng/ml; p = 0.05). The area under the coronary sinus histamine concentration-vs.-time curve ("total cardiac histamine efflux") correlated directly with the total number of ventricular premature contractions during the first 30 min after coronary artery occlusion (r = 0.81; p less than 0.005; n = 10), and with infarct size (r = 0.91; p less than 0.01; n = 6). Thus, during acute myocardial ischemia, the coronary sinus histamine concentration increases simultaneously with the development of early ischemic ventricular arrhythmias and in proportion to their severity.     

Protection by carbocromene and molsidomine against arrhythmias occurring during coronary artery occlusion and reperfusion in dogs

We studied the effects of carbocromene (4 mg/kg plus 40 micrograms/kg/min i.v.) and molsidomine (0.1 mg/kg plus 2 micrograms/kg/min i.v.) on arrhythmias occurring during 90-min occlusion and 30-min reperfusion of the left anterior descending coronary artery in anesthetized dogs. Both drugs reduced the incidence of left ventricular (LV) premature depolarization during ligation (39% after carbocromene and 33% after molsidomine vs. 80% in controls; both p less than 0.05) and tachycardia (44% after carbocromene and 38% after molsidomine vs. 85% in controls; p less than 0.05). During reperfusion, the incidence of LV fibrillation was reduced in the carbocromene- (6 vs. 38% in controls; p less than 0.05) and molsidomine-treated dogs (10 vs. 38% in controls; p less than 0.05). The high incidence of ectopic activity and the ST segment elevation occurring after coronary ligation in control animals were prevented by both drugs. The hemodynamic deterioration after coronary occlusion, i.e., increase in blood pressure, LV systolic and end-diastolic pressures, LV dP/dtmax, and tachycardia observed in controls, was prevented by carbocromene. Molsidomine reduced blood pressure and LV pressure by 18 and 27% (p less than 0.05), respectively, during coronary occlusion. During reperfusion, no hemodynamic alterations occurred in the drug-treated animals. We conclude that carbocromene reduced the electrophysiologic consequences of acute ischemia by hemodynamic and anti-ischemic effects on heart metabolism. Molsidomine protected the jeopardized heart by a similar attenuation of hemodynamic derangement after coronary occlusion and perhaps by influencing prostanoid release from the ischemic myocardium.