Distribution of microcystins in various organs (heart, liver, intestine, gonad, brain, kidney and lung) of Wistar rat via intravenous injection

The distribution of microcystins (MCs) in various tissues of Wistar rats was studied under laboratory conditions. Rats were injected intravenously (i.v.) with extracted MCs at a dose of 80 mu g MC-LRequivalent/kg body weight. MCs concentrations in various tissues were detected at 1, 2. 4, 6, 12 and 24 h post-injection using liquid chromatography-mass spectrometry (LC-MS). The highest concentration of MCs was found in kidney (0.034-0.295 mu g/g dry weight), followed by lung (0.007-0.067 mu g/g dry weight), stomach (0.010-0.058 mu g/g dry weight) and liver (0.003-0.052 mu g/g dry weight). The maximum MCs content in the whole body of rat, 2.9% of the injected dose, was observed at 2 h post-injection. MCs concentration was higher in kidney than in liver during the experiment, and two peaks of MCs concentration (at 2 and 24 h, respectively) were observed in kidney, indicating that MCs can be excreted directly via kidney of rat. Though heart, intestine, spleen, brain, gonad and stomach contained less than 0.2% of injected MCs during the whole experiment stage, the presence of MCs in these tissues represents potential damage to them. (c) 2008 Elsevier Ltd. All Fights reserved.

Propofol facilitates the development of long-term depression (LTD) and impairs the maintenance of long-term potentiation (LTP) in the CA1 region of the hippocampus of anesthetized rats

Memory is sensitive to the short-acting anesthetic (2,6-diisopropylphenol) propofol, but the underlying mechanism is little known. Here, we have examined the effects of propofol on synaptic plasticity in the CA1 region of the hippocampus of anesthetized rats. We found that low dose of propofol (20 mg/kg, i.p.) did not affect the basal transmission, but enhanced prominently the development of long-term depression (LTD) and impaired the maintenance of long-term potentiation (LTP). The impairment of LTP maintenance and enhancement of LTD development may contribute to propofol-induced deficits in memory following propofol anesthesia. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

γ-氨基丁酸受体和甘氨酸受体在大鼠丙泊酚麻醉中的作用

目的 研究丙泊酚对大鼠海马CA1区电刺激诱发兴奋性突触后电流(EPSC)的影响,分析γ-氨基丁酸(GABA)受体和甘氨酸受体在丙泊酚麻醉中的作用.方法 断头法分离wistar大鼠(13～19 d)海马半脑,切出400 μm厚度的海马脑片,全细胞膜片钳技术记录CA1区锥体神经元EPSC.80张脑片分为八组:脂肪乳剂组,50 μmol/L丙泊酚组,100 μmol/L丙泊酚组,200 μmol/L丙泊酚组,SR95531组,士的宁组,SR95531+100 μmol/L丙泊酚组,士的宁+100 μmol/L丙泊酚组,每组10张.SR95531+100 μmol/L丙泊酚组和士的宁+100 μmol/L丙泊酚组先在循环液中加入10 μmol/L SR95531或4 μmol/L士的宁预孵脑片30 min.八组均记录基础EPSC 10 min,然后加入不同药物,继续记录EPSC 40 min.膜钳制电压为-70 mV.结果 脂肪乳剂、SR95531和士的宁对EP-SC幅值无影响;丙泊酚呈剂量依赖性的抑制EPSC幅值,50、100、200 μmol/L丙泊酚最大抑制EPSC幅值为14.4%、52.3%、67.8%;SR95531+100 μmol/L丙泊酚组加入丙泊酚后,EPSC幅值基本无改变;士的宁+100 μmol/L丙泊酚组加入丙泊酚后,EPSC幅值仍然下降,最大抑制程度为34.7%.结论 丙泊酚主要通过增强GABAA受体功能使兴奋性突触活动降低,甘氨酸受体在其中起到协同和调节作用.

Quantitative Determination of Microcystins in Rat Plasma by LC-ESI Tandem MS

A rapid and sensitive method was developed and validated for the determination of MCYST (microcystin)-RR, -LR, and [Dha(7)] MCYST-LR in rat plasma by liquid chromatography-tandem mass spectrometry. The analytes were extracted from rat plasma by protein precipitation, followed by solid-phase extraction. Liquid chromatography with electrospray ionization mass spectrometry, operating in selected reaction monitoring (SRM) mode, was used to quantify MCYST-RR, -LR, and [Dha(7)] MCYST-LR in rat plasma. The recoveries for each analyte in rat plasma ranged from 70.8 to 88.7%. The calibration curve was linear within the range from 0.005 to 1.25 mu g mL(-1). The limit of detection were 1.4, 1.0, 0.6 ng mL(-1) for MCYST-RR, -LR, and [Dha(7)] MCYST-LR. The overall precision was determined on three different days. The values for within- and between-day precision in rat plasma were within 15%. This method was applied to the identification and quantification of microcystins in rat plasma with acute exposure of microcystins via intravenous injection.

Gadolinium heteropoly complex K-17[Gd(P2W17O61)(2)] as a potential MRI contrast agent

Gadolinium heteropoly complex K-17[Gd(P2W17O61)(2)] has been evaluated by in vitro and in vivo experiments as a potential contrast agent for magnetic resonance imaging (MRI). The thermal analysis and conductivity study indicate that this complex has good thermal stability and wide pH stability range. The T-1 relaxivity is 7.59 mM(-1) s(-1) in aqueous solution and 7.97 mM(-1) s(-1) in 0.725 mmol l(-1) bovine serum albumin (BSA) solution at 25degreesC and 9.39 T, respectively. MR imaging of three male Sprague-Dawley rats showed remarkable enhancement in rat liver after intravenous injection, which persisted longer than with Gd-DTPA. The signal intensity increased by 57.1 +/- 16.9% during the whole imaging period at 0.082 mmol kg(-1) dose. Our preliminary in vitro and in vivo studies indicate that K-17[Gd(P2W17O61)(2)] is a potential liver-specific MRI contrast agent.