黄芩苷在多壁碳纳米管修饰玻碳电极上的电化学行为及其测定

目的建立了检测黄芩苷含量的电化学分析新方法。方法采用循环伏安法研究黄芩苷在多壁碳纳米管修饰玻碳电极上的电化学行为及其电极反应机理,以差示脉冲伏安法建立了检测黄芩苷含量的电化学分析新方法。结果在优化的条件下,电化学信号强度电流值I与黄芩苷浓度在1×10-9~5×10-7mol.L-1和6×10-7~5×10-6mol.L-1范围呈线性关系,相关系数为0.9956和0.9934。该方法的黄芩苷浓度检出限为1×10-10mol.L-1,平行测定6次得RSD为1.04%,回收率为98.0~102.0%。结论利用多壁碳纳米管修饰的玻碳电极分析法,建立了测定黄酮类药物黄芩苷的含量新方法,并应用于清开灵注射液中黄芩提取物（黄芩苷计）的含量测定,结果令人满意。     

羟喜树碱在玻碳电极上的直接电化学行为研究

目的 建立直接电化学检测羟喜树碱含量的方法.方法 本文采用伏安法研究羟喜树碱在玻碳电极上的直接电化学行为.在磷酸盐缓冲液中(pH5.0),在-0.2～ 0.4 V范围内羟喜树碱在玻碳电极表面是受吸附控制,发生准可逆两电子转移电极反应过程,电子转移系数α=0.479;并以差示脉冲伏安法建立了检测羟喜树碱含量的新方法.结果 在富集电位 0.8 V,富集时间 30s,利用差示脉冲伏安法可测得其氧化峰电流Ip与浓度分别在2.0×10-7～5.0×10-6mol·L-1内呈良好的线性关系,最低检出限为5.0×10-8mol·L-1.结论 本法操作简单、快速、灵敏、准确,可为羟喜树碱药物质量的控制和检测提供了一种简便的方法.     

Novel voltammetric responses of a 1,1′-ferrocene bis(methylene aza-18-crown-6) receptor to group 1 and 2 metal cations in acetonitrile

A 1,1′-ferrocene bis(methylene aza-18-crown-6) ligand (L) and its inclusion complexes with Na⁺, K⁺, Ba²⁺ and Mg²⁺ are studied in acetonitrile by cyclic and square wave voltammetry. The ligand-metal complex stoichiometry is found to vary from 1:1 to 1:2 with increasing concentration of the metal cation. There is also a binding selectivity for dications over monocations. Simultaneous addition of Mg²⁺ and Ba²⁺ gives rise to a novel voltammetric feature which is rationalised by the formation of three different species; the symmetrical homobimetallic complexes, L—2Ba²⁺ and L—2Mg²⁺, and the asymmetrical heterobimetallic complex, L—Ba²⁺—Mg²⁺. L is therefore a redox active receptor capable of the simultaneous electrochemical recognition of different metal cations. An electrostatic model is proposed to account for the observed changes in the mean potential of L upon cation complexation.     

Dopamine release and uptake rates both decrease in the partially denervated striatum in proportion to the loss of dopamine terminals

The present study tested the hypothesis that normal concentrations of extracellular dopamine are preserved in the partially denervated striatum without active compensatory changes in dopamine uptake or release. One to four weeks after adult rats were unilaterally lesioned with 6-hydroxydopamine, fast-scan cyclic voltammetry at Nafion-coated, carbon-fiber microelectrodes was used to monitor extracellular dopamine levels in vivo, under urethane anesthesia. Simultaneous voltammetric recordings were collected in the lesioned and contralateral control striata. Extracellular dopamine was elicited by bilateral electrical stimulation of the medial forebrain bundle. A 20 Hz stimulation evoked similar concentrations of extracellular dopamine in both lesioned and control striata, although tissue dopamine was decreased 30–70% in lesioned striata, as determined subsequently by HPLC-EC. However, kinetic analysis of the voltammetric recordings revealed that the concentration of dopamine released per stimulus pulse and V_max for dopamine uptake decreased in proportion to the magnitude of the lesion. These data support the hypothesis that normal extracellular dopamine levels can be generated in the partially lesioned striatum in the absence of active neuronal compensation. These results also suggest that passive mechanisms involved in the regulation of extracellular dopamine play an important role in maintaining function during the preclinical or presymptomatic phase of Parkinson's disease.© 1997 Elsevier Science B.V. All rights reserved.     

In vivo studies on the enhancement of serotonin reuptake by tianeptine

The present study investigates the in vivo effects of the serotonin uptake enhancer tianeptine. The serotonin metabolite, 5-hydroxy-indolacetic acid (5-HIAA) was measured by in vivo voltammetry and carbon fiber electrodes chronically implanted in different brain areas of freely moving rats. Tianeptine (10 mg/kg i.p.) increased extracellular 5-HIAA in the hippocampus and hypothalamus. The interaction between tianeptine and drugs known to interfere with the uptake or release of serotonin (sertraline, buspirone, D-norfenfluramine) was then studied and, to ascertain the in vivo pharmacological relevance of tianeptine's effects, its ability to reduce the serotoninergic syndrome was evaluated. Both the biochemical and behavioral data indicate that in vivo tianeptine's effects on the serotoninergic system are likely to be due to serotonin uptake enhancement.     

Antagonistic effects of stimulation of the paramedian reticular nucleus in the rat medulla oblongata and of amphetamine on locomotor activity and striatal release of dopamine-like material

Summary The effects of stimulation of the paramedian reticular nucleus (PRN) in the rat medulla oblongata on both amphetamine-induced locomotor activity and striatal release of dopamine-like material were assessed. PRN stimulation (by intra-PRN injection of the excitatory amino acid, kainic acid) decreased vertical motion and total distance travelled, and increased postural freezing, in freely moving rats. On the other hand, a small dose (e.g. 1.25 mg/kg, i.p.) of amphetamine increased locomotor activity (including horizontal motion, vertical motion, total distance travelled and lines crossed counts), increased the number of turnings (both clockwise and anti-clockwise), induced locomotor stereotypy (including both gamma value and number of trip types), and inhibited postural freezing. The changes in activity induced by amphetamine administration were suppressed following PRN stimulation. In vivo voltammetric data revealed that electrical stimulation of the PRN decreased the release of dopamine-like material in the corpus striatum. This effect could be mimicked by intra-PRN injection of kainic acid in anesthetized rats. In contrast, i.p. administration of amphetamine increased the release of dopamine-like material in the corpus striatum. Furthermore, the enhanced release of dopamine-like material induced by amphetamine was attenuated by simultaneous stimulation of the PRN. The results reported here indicate that PRN stimulation decreases the striatal dopamine release and results in attenuation of the amphetamine-induced locomotor activity responses in rats. Correspondence to M. T. Lin at the above address     

人体中痕量铊测定方法的研究及应用

本文用分力式聚四氟乙烯高压溶样器做人体样品预处理,有效地防止了消化过程中铊的挥发损失。应用微分脉冲阳极溶出伏安法研究了人体中痕量铊的测定方法,通过实验确定了最佳测试条件,方法检出下限为2.4×10~(-10)mol/L。实测人体样品,铊的回收率为100.9±7.8％(±SD),变异系数CV=7.7％。用本法测定了24例心脏病患儿的发铊,获得满意结果。     

Differential effects of amfonelic acid on the haloperidol- and clozapine-induced increase in extracellular DOPAC in the nucleus accumbens and the striatum.

This study compares the effects of the nonamphetamine stimulant amfonelic acid on the increase in extracellular 3,4-dihydroxyphenylacetic acid (DOPAC) induced by haloperidol and clozapine in the nucleus accumbens and the striatum of anaesthetized rats. DOPAC was simultaneously recorded in both regions using differential pulse voltammetry with electrically pretreated carbon fibre electrodes. Amfonelic acid (2.5 mg/kg s.c.) did not alter basal striatal DOPAC but produced a significant reduction in extracellular DOPAC in the nucleus accumbens. Haloperidol (1 mg/kg s.c.) increased extracellular DOPAC in both regions. When amfonelic acid was injected 5 min before haloperidol, the increase in DOPAC was potentiated in both the nucleus accumbens and the striatum but with a greater effect in the striatum. Clozapine (30 mg/kg i.p.) increased extracellular DOPAC in both regions, an effect partially attenuated by amfonelic acid in both regions but to a greater extent in the striatum. When ritanserin (5 mg/kg i.p.), a serotonergic antagonist (5-HT-2), was co-administered with haloperidol, the potentiation by amfonelic acid of the increase in extracellular DOPAC induced by haloperidol was attenuated in both the nucleus accumbens and the striatum. The present results confirm that amfonelic acid can be used to discriminate neurochemically between haloperidol and clozapine in vivo. The effects of amfonelic acid on the neuroleptic-induced changes in extracellular DOPAC were greater in the striatum than the nucleus accumbens. These results further demonstrate that both neuroleptics increase dopamine metabolism in the two brain regions but by different mechanisms, supporting the view that the regulation of dopamine metabolism differs in the two regions.(ABSTRACT TRUNCATED AT 250 WORDS)