On the Specificity of Verapamil as a Calcium Channel-Blocker

Norris, D.K.; Bradford, H. F.

doi:10.1097/00132586-198602000-00008

Cited by 2 publications

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“…Our experimental approach does not provide direct evidence of whether Ca2 + leaving the extracellular space (reflected in a drop in the ion concentration of the perfusate) enters the intraneuronal compartment. However, most studies have shown that veratridine and KCl-activation raises the cytoplasmic Ca2 + concentration in nerve terminals and cell soma (Norris & Bradford, 1985;Mody & Heinemann, 1986) and Ca2+ influx stimulated by veratridine and KCl proved to be mediated by VSCC (Nachshen & Blaustein, 1979). Moreover, Ca2+ influx by glial cells is not an important site for Ca2 + fluxes induced by these depolarizing agents and excitotoxins (Kelly & Krnjevic, 1967;Bowman & Kimelberg, 1984).…”

Section: Discussionmentioning

confidence: 99%

Effects of Ca²⁺antagonists on glutamate release and Ca²⁺influx in the hippocampus with in vivo intracerebral microdialysis

Lü

Zhang

Zhao

et al. 1991

British J Pharmacology

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1The extracellular glutamate content and Ca2+ level in vivo in rat hippocampus were measured by brain microdialysis following administration of two depolarizing agents (veratridine, KCl) and quinolinic acid (Quin). 2 The two depolarizing agents increased the extracellular glutamate level (to between 280 and 320% basal) and decreased the extracellular Ca2" content (to 48% of basal). However, Quin did not change the glutamate level but decreased the Ca2+ content. 3 The effects of Ca2+ antagonists on the changes of glutamate and Ca2+ level were evaluated in this experimental model. At a dose of 0.5 mgkg-1, i.v., nimodipine (L-type channel blocker) did not produce significant changes in the stimulated-glutamate release. A statistically significant inhibition of Ca2 + influx was observed at a dose of 0.05 mg kg'-. In contrast, in those animals receiving the N-type Ca2 + antagonist, daurisoline (0.1, 1 or 5 mg kg ',i.v.), a potent attenuation of both glutamate release and Ca2 + influx was found. 4 We propose that the pharmacological properties of Ca2 + influx and of neurotransmitter release differ and that nimodipine-sensitive L-type channels may not be very common in nerve terminals but are localized in cell soma. Daurisoline-sensitive N-type channels in nerve terminals have a much greater influence on excitatory amino acid release.

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Section: Discussionmentioning

confidence: 99%

Effects of Ca²⁺antagonists on glutamate release and Ca²⁺influx in the hippocampus with in vivo intracerebral microdialysis

Lü

Zhang

Zhao

et al. 1991

British J Pharmacology

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“…Although it is well known that ion channels play an important role in signalling and control of morphogenesis in plants, their distribution in higher plant tissues has not been described yet. Phenylalkylamines (PAAs) are pharmacological drugs able to block specifically the L-type Ca 2+ -channel activity in animal cells (Norris and Bradford, 1985) and has been shown to block the entry of calcium into plant cells (Thuleau et al, 1990). A fluorescently labelled PAA, DM-Bodipy PAA, has been used as a probe for labelling Ca 2+ -channels in animal cell membranes (Knaus et al, 1992) and in sunflower protoplasts (Valle´e et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Somatic embryogenesis by liquid culture of epidermal layers in sunflower: from genetic control to cell development

Sarrafi

Flores-Berrios

XuHan

et al. 2005

Plant Cell Tiss Organ Cult

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Embryos were obtained using liquid medium culture of sunflower hypocotyl epidermis layers according to the Pe´lissier et al. (1990) method. In the present work we identified genetic factors controlling somatic embryogenesis and we evidenced the role of ionic channels in embryogenic tissues. Two traits, the number of embryogenic explants (EE) and the number of embryos (EM) were scored in 74 recombinant inbred lines (RILs) from a cross between lines PAC-2 and RHA-266. Analysis of variance indicated the existence of highly significant differences among the parental genotypes and their RILs. Heritability for the somatic embryogenesis traits studied were high (0.64 for EE and 0.77 for EM). Four quantitative trait loci (QTLs) for EE and seven for EM were detected using composite interval mapping. The QTLs for EE explained 48% of the phenotypic variation while the QTLs for EM explained about 89% of the variation, thus revealing several genomic regions related to somatic embryogenesis control in sunflower. In order to study the distribution of ion channels in somatic embryos as compared to zygotic ones, we used a fluorescentlabelled phenylalkylamine, DM-Bodipy PAA, as a probe. Fluorescence labelling was determined by confocal microscopy. The probe intensively labelled the protoderm and epidermis cells in both zygotic and somatic embryos. Callus exhibited labelling on sites where somatic embryos developed. Considering that the location of phenylalkylamine (PAA) binding sites is related to the distribution of ion channels, the high intensity in the protoderm and epidermis of embryos, point to similar properties and functions and their key role in embryo development.Abbreviations: EE -embryogenic explants; EM -number of embryos; PAA -phenylalkylamine; QTLsquantitative trait loci; RILs -recombinant inbred lines

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On the Specificity of Verapamil as a Calcium Channel-Blocker

Cited by 2 publications

References 0 publications

Effects of Ca²⁺antagonists on glutamate release and Ca²⁺influx in the hippocampus with in vivo intracerebral microdialysis

Effects of Ca²⁺antagonists on glutamate release and Ca²⁺influx in the hippocampus with in vivo intracerebral microdialysis

Somatic embryogenesis by liquid culture of epidermal layers in sunflower: from genetic control to cell development

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On the Specificity of Verapamil as a Calcium Channel-Blocker

Cited by 2 publications

References 0 publications

Effects of Ca2+antagonists on glutamate release and Ca2+influx in the hippocampus with in vivo intracerebral microdialysis

Effects of Ca2+antagonists on glutamate release and Ca2+influx in the hippocampus with in vivo intracerebral microdialysis

Somatic embryogenesis by liquid culture of epidermal layers in sunflower: from genetic control to cell development

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Effects of Ca²⁺antagonists on glutamate release and Ca²⁺influx in the hippocampus with in vivo intracerebral microdialysis

Effects of Ca²⁺antagonists on glutamate release and Ca²⁺influx in the hippocampus with in vivo intracerebral microdialysis