The Determination of Brain Magnesium and Zinc Levels by a Dual-Probe Microdialysis and Graphite Furnace Atomic Absorption Spectrometry

Yang, Dar-Yu; Lee, Jen-Bin; Lin, Ming‐Cheng; Huang, Yeou‐Lih; Liu, Hong‐Wen; Liang, Yea-Jiuan; Cheng, Fu‐Chou

doi:10.1080/07315724.2004.10719402

Cited by 22 publications

(10 citation statements)

References 15 publications

(15 reference statements)

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“…It is known that under pathological conditions, such as brain ischemia, extracellular Ca 2+ and Mg 2+ decrease greatly [6], [65]. This may directly enhance synaptic transmission according to our finding.…”

Section: Discussionsupporting

confidence: 76%

An Inhibitory Effect of Extracellular Ca2+ on Ca2+-Dependent Exocytosis

et al. 2011

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AimNeurotransmitter release is elicited by an elevation of intracellular Ca2+ concentration ([Ca2+]i). The action potential triggers Ca2+ influx through Ca2+ channels which causes local changes of [Ca2+]i for vesicle release. However, any direct role of extracellular Ca2+ (besides Ca2+ influx) on Ca2+-dependent exocytosis remains elusive. Here we set out to investigate this possibility on rat dorsal root ganglion (DRG) neurons and chromaffin cells, widely used models for studying vesicle exocytosis.ResultsUsing photolysis of caged Ca2+ and caffeine-induced release of stored Ca2+, we found that extracellular Ca2+ inhibited exocytosis following moderate [Ca2+]i rises (2–3 µM). The IC50 for extracellular Ca2+ inhibition of exocytosis (ECIE) was 1.38 mM and a physiological reduction (∼30%) of extracellular Ca2+ concentration ([Ca2+]o) significantly increased the evoked exocytosis. At the single vesicle level, quantal size and release frequency were also altered by physiological [Ca2+]o. The calcimimetics Mg2+, Cd2+, G418, and neomycin all inhibited exocytosis. The extracellular Ca2+-sensing receptor (CaSR) was not involved because specific drugs and knockdown of CaSR in DRG neurons did not affect ECIE.Conclusion/SignificanceAs an extension of the classic Ca2+ hypothesis of synaptic release, physiological levels of extracellular Ca2+ play dual roles in evoked exocytosis by providing a source of Ca2+ influx, and by directly regulating quantal size and release probability in neuronal cells.

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Section: Discussionsupporting

confidence: 76%

An Inhibitory Effect of Extracellular Ca2+ on Ca2+-Dependent Exocytosis

et al. 2011

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“…2). Our previous experiments proved that during cerebral ischemia, the mean Mg 2+ level significantly decreased to approximately 41% and 65% of the baseline levels (Lin et al, 2004b;Yang et al, 2004). Significant neuroprotection with only magnesium has been observed in different models of focal cerebral ischemia, with infarct volume reductions between 25 and 61% (Muir, 2001).…”

Section: Discussionmentioning

confidence: 86%

Ginkgo biloba Leaf Extract (EGb761) Combined with Neuroprotective Agents Reduces the Infarct Volumes of Gerbil Ischemic Brain

et al. 2006

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Ginkgo biloba exerts many pharmacological actions. It possesses antioxidant properties, the ability of neurotransmitter/receptor modulation and antiplatelet activation factor. This research is designed to investigate the neuroprotective effects of long-term treatment with EGb761 (a standard form of the extract of Ginkgo biloba leaf) in combination with MgSO(4), FK506, or MK-801 on the infarct volume of male gerbils' brain induced by unilateral middle cerebral artery occlusion (MCAO). Thirty-five gerbils fed a standard diet were intragastrically given water or EGb761 (100 mg/kg/day) for one week. Five randomized groups were established: control (n = 7), EGb761 (n = 8), EGb761 + MgSO(4) (n = 7), EGb761 + FK506 (n = 7), and EGb761 + MK-801 (n = 6). The three drug-combination groups were injected with MgSO(4) (90 mg/kg), FK506 (0.5 mg/kg), or MK-801 (1 mg/kg), respectively 30 min before MCAO. Gerbils were anesthetized and craniectomized to expose the right middle cerebral artery (MCA). The right MCA was constricted with an 8-0 suture to produce a permanent ligation for 24 hours. Postmortem infarct volumes were determined by quantitative image analysis of 2,3,5-triphenyltetrazolium chloride (TTC)-stained brain sections. Results showed that the total infarct volumes of the four treated groups either EGb761 alone or in combination with drugs were lower than the control group by 36.1% (EGb761 alone), 40.3% (EGb761 + MgSO(4)), 35.3% (EGb761 + FK506), and 56.4% (EGb761 + MK-801), respectively (p < 0.01). The main affected areas of the brain in the four treated groups were significantly focused between 4 and 6 mm from the frontal pole, when compared to the control group (p < 0.01). All animals in the five groups had infarctions in both cortex and subcortex. These results indicate that long-term pre-treatment of EGb761 administered either alone or in combination with drugs significantly effective neuroprotection on infarct volume in gerbil ischemic brains.

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“…Furthermore, the higher atom density and longer residence time in the graphite tube improve ETAAS detection limits by a factor of up to 1,000-fold-down to the submicrogram-per-liter range-compared to flame AAS. In view of its advantages, several on-line and off-line methods based on the combination of microdialysis sampling and ETAAS have been developed for in vivo determination of Zn, Mn, Cu, Fe, and Pt (cisplatin) (Nakashima et al, 1997;Tokunaga et al, 2000;Leveque et al, 2001Leveque et al, , 2003Lin et al, 2004Yang et al, 2004). Because only small-volume microdialysates that contain very low concentrations of analyte ions are required for analyses, and because it always takes a long time to collect the data for biokinetics studies for in vivo animal experiments, the resulting reduction in contamination and losses of analyte species and minimized complexity of the operation procedures are key factors that lead to the attractiveness of in vivo determination of trace metal ions.…”

Section: Atomic Spectrometric Detectionmentioning

confidence: 99%

In vivomonitoring of the transfer kinetics of trace elements in animal brains with hyphenated inductively coupled plasma mass spectrometry techniques

Su¹,

Sun²,

Tzeng³

et al. 2009

Mass Spectrom. Rev.

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The roles of metal ions to sustain normal function and to cause dysfunction of neurological systems have been confirmed by various studies. However, because of the lack of adequate analytical method to monitor the transfer kinetics of metal ions in the brain of a living animal, research on the physiopathological roles of metal ions in the CNS remains in its early stages and more analytical efforts are still needed. To explicitly model the possible links between metal ions and physiopathological alterations, it is essential to develop in vivo monitoring techniques that can bridge the gap between metalloneurochemistry and neurophysiopathology. Although inductively coupled plasma mass spectrometry (ICP-MS) is a very powerful technique for multiple trace element analyses, when dealing with chemically complex microdialysis samples, the detection capability is largely limited by instrumental sensitivity, selectivity, and contamination that arise from the experimental procedure. As a result, in recent years several high efficient and clean on-line sample pretreatment systems have been developed and combined with microdialysis and ICP-MS for the continuous and in vivo determination of the concentration-time profiles of metal ions in the extracellular space of rat brain. This article reviews the research relevant to the development of analytical techniques for the in vivo determination of dynamic variation in the concentration levels of metal ions in a living animal.

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The Determination of Brain Magnesium and Zinc Levels by a Dual-Probe Microdialysis and Graphite Furnace Atomic Absorption Spectrometry

Abstract: The derangement of extracellular Mg and Zn could be important in the progression of cell injury and may be associated with cerebral ischemia insult.

Cited by 22 publications

References 15 publications

An Inhibitory Effect of Extracellular Ca2+ on Ca2+-Dependent Exocytosis

An Inhibitory Effect of Extracellular Ca2+ on Ca2+-Dependent Exocytosis

Ginkgo biloba Leaf Extract (EGb761) Combined with Neuroprotective Agents Reduces the Infarct Volumes of Gerbil Ischemic Brain

In vivomonitoring of the transfer kinetics of trace elements in animal brains with hyphenated inductively coupled plasma mass spectrometry techniques

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